Particulate wood preservative and method for producing the same

ABSTRACT

A wood preservative includes injectable particles comprising one or more sparingly soluble copper salts. The copper-based particles are sufficiently insoluble so as to not be easily removed by leaching but are sufficiently soluble to exhibit toxicity to primary organisms primarily responsible for the decay of the wood. Exemplary particles contain for example copper hydroxide, basic copper carbonate, copper carbonate, basic copper sulfates including particularly tribasic copper sulfate, basic copper nitrates, copper oxychlorides, copper borates, basic copper borates, and mixtures thereof. The particles typically have a size distribution in which at least 50% of particles have a diameter smaller than 0.25 μm, 0.2 μm, or 0.15 μm. At least about 20% and even more than 75% of the weight of the particles may be composed of the substantially crystalline copper salt. Wood or a wood product may be impregnated with copper based particles of the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/777,649, filed Feb. 26, 2013, which is a continuation of U.S.application Ser. No. 12/458,522, filed Jul. 15, 2009, now U.S. Pat. No.8,409,627, which is a continuation of U.S. application Ser. No.10/868,967, filed Jun. 17, 2004, now abandoned, which claims priority tothe following U.S. Provisional applications 60/478,822, 60/478,827,60/478,825, and 60/478,820, all of which were filed on Jun. 17, 2003,and also to U.S. Provisional application 60/571,535 filed on May 17,2004, each of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to wood preservatives, particularly woodpreservatives comprising particles including one or more coppercompounds. More particularly, the invention relates to a woodpreservative comprising injectable particles of sparingly soluble coppersalts, as well as methods to prepare the wood preservative, and methodsof preserving wood using the wood preservatives.

BACKGROUND OF THE INVENTION

The production of wood which has been treated to inhibit biologicaldecomposition is well known. Decay is caused by fungi that feed oncellulose or lignin of wood. Such organisms causing wood decompositioninclude: basidiomycetes such as Gloeophyllum trabeum (brown rot),Trametes versicolor (white rot), Serpula lacrymans (dry rot) andConiophora puteana. Soft rot attacks the surface of almost all hard andsoftwoods, and it favors wet conditions. Most of these fungi requirefood and moisture, e.g., moisture contents in wood of greater than 20%are conducive to fungal growth. Dry rot is tenacious, as it can grow indry wood. Insects are also major causes of wood deterioration. Exemplaryorganisms causing wood decomposition include coleopterans such asAnobium punctatum (furniture beetle), Hylotrupes bajulus (houselonghorn) and Xestobium rufovillorum (death watch beetle); hymenopteranssuch as termites and carpenter ants; and also by marine borers and/orwasps. Finally, termites are ubiquitous, and termite damage is estimatedin the United States alone to be about $2 billion per year.

The production of wood based composite products has increaseddramatically in recent years. Oriented strandboard (OSB) productionexceeded that of plywood in 2000. The use of medium density fiberboardand hardboard panel products likewise has increased dramatically overthe last couple of decades. However, these products are typically usedin interior applications where attack from insects or decay fungi islimited, because it has been found that these products are particularlysusceptible to attack by biological agents such as decay fungi andtermites.

Preservatives are used to treat wood to resist insect attack and decay.The commercially used preservatives are separated into three basiccategories, based primarily on the mode of application-waterborne,creosote, and oil borne preservatives. Waterborne preservatives includechromated copper arsenate (CCA), ammoniacal copper quat (ACQ, which isbelieved to be Copper-MEA-Carbonate and a quaternary amine), ammoniacalcopper zinc arsenate (ACZA), and ammoniacal copper arsenate (ACA). Woodtreated with these chemicals sometimes turns green or grey-green becauseof a chemical reaction between copper in the preservative and the sun'sultraviolet rays. The preservatives leach into the soil over time,especially those made without chromium, when exposed to weather.Creosote does not easily leach into soil, and it is not corrosive tometals, but it can not be painted and it leaves a dark, oily surfacethat has a strong odor. Oil borne preservatives are made of certaincompounds dissolved in light petroleum oils, including pentachlorophenol(commonly known as “penta”), copper naphthenate, andcopper-8-quinolinolate. These preservatives leave a surface that oftenis non-paintable, and the surface of the wood can be dark andunnaturally colored.

Modern organic biocides are considered to be relatively environmentallybenign and not expected to pose the problems associated with CCA-treatedlumber. Biocides such as tebuconazole are quite soluble in commonorganic solvents, while others such as chlorothalonil possess only lowsolubility. The solubility of organic biocides affects the markets forwhich the biocide-treated wood products are appropriate. Biocides withgood solubility can be dissolved at high concentrations in a smallamount of organic solvents, and that solution can be dispersed in waterwith appropriate emulsifiers to produce an aqueous emulsion. Theemulsion can be used in conventional pressure treatments for lumber andwood treated in such a manner, and can be used in products such asdecking where the treated wood will come into contact with humans.Biocides which possess low solubility must be incorporated into wood ina solution of a hydrocarbon oil, such as AWPA P9 Type A, and theresulting organic solution is used to treat wood directly. Wood treatedin this way can be used only for industrial applications, such asutility poles and railway ties, because the oil is irritating to humanskin.

The primary preserved wood product has historically been southern pinelumber treated with chromated copper arsenate (CCA). Most of thistreated lumber was used for decks, fencing and landscape timbers. Therehas recently been raised concerns about the safety and health effects ofCCA as a wood preservative, primarily relating to the arsenic contentbut also to the chromium content. In 2003/2004, due in part toregulatory guidelines and to concerns about safety, there has been asubstantial cessation of use of CCA-treated products. A new generationof copper containing wood preservatives uses a form of copper that issoluble. Known preservatives include copper alkanolamine complexes,copper polyaspartic acid complex, alkaline copper quaternary, copperazole, copper boron azole, copper bis(dimethyldithiocarbamate),ammoniacal copper citrate, copper citrate, and the copper ethanolaminecarbonate. In practice, the principal criterion for commercialacceptance, assuming treatment efficacy, is cost. Of the manycompositions listed above, only two soluble copper containing woodpreservatives have found commercial acceptance: 1) the copperethanolamine carbonate manufactured for example according to the processdisclosed in U.S. Pat. No. 6,646,147 and 2) copper boron azole. Thereare, however, several problems with these new copper-containingpreservatives.

The soluble copper containing wood preservatives are very leachable,compared to CCA. One study has shown that as much as 80 percent of thecopper from a copper amine carbonate complex is removed in about 10years under a given set of field conditions. Under severe conditions,such as the those used for the American Wood Preserving Association'sstandard leaching test, these products are quickly leached from thewood. For example, we found that 77% by weight of a Cu-monoethanolaminepreservative was leached from the preserved wood in 14 days. Thisleaching is of concern for at least two reasons: 1) removal of thecopper portion of the pesticide from the wood by leaching willcompromise the long term efficacy of the formulation and 2) the leachedcopper causes concern that the environment will be contaminated. Whilemost animals tolerate copper, copper is extremely toxic to certain fishat sub-part per million levels. Common ranges for EC₅₀ for copper arebetween 2 and 12 micrograms per liter. Another study reported followingthe Synthetic Precipitation Leaching Procedure. The study results showedthat the leachate from CCA-treated wood contained about 4 mg copper perliter; leachate from copper boron azole-treated wood contained about 28mg copper per liter; leachate from copper bis(dimethyldithiocarbamate)treated wood had 7 to 8 mg copper per liter; leachate from alkalinecopper quaternary treated wood had 29 mg copper per liter; and leachatefrom copper citrate treated wood had 62 mg copper per liter. However,copper concentrations depend in part on copper concentration, and CCAhad about 7% of total copper leach, the alkaline copper quaternarypreservative had about 12% of the total copper leach, while the copperboron azole had about 22% of the total copper leach during the SyntheticPrecipitation Leaching Procedure. Copper leaching is such a problem thatsome states do not allow use of wood treated with the soluble coppercontaining wood preservatives near waterways.

Another concern with soluble copper preservative products generally isthat most preservative materials are manufactured at one of severalcentral locations but are used in disparate areas and must be shipped,sometimes substantial distances. The cost of providing and transportingthe liquid carrier for these soluble products can be considerable, andthe likelihood of an extreme biological impact is very high iftransported soluble copper wood preservative material is spilled oraccidentally released near a waterway.

Further, unlike CCA, all of these soluble copper containing woodpreservatives require a second organic biocide to be effective againstsome biological species. Therefore, wood preserved with these solublecopper containing wood preservatives also contains a second biocide thatis efficacious against one or more particularly troublesome species.Oil-soluble biocides such as a copper(II)-sulfited tannin extractcomplex (epicatechins) can be dissolved in light oils, emulsified inwater, and injected into the wood, as is disclosed in U.S. Pat. No.4,988,545. Alternatively, the second biocide is often slightly watersoluble or emulsified, and may be composed of a triazole group or aquaternary amine group or a nitroso-amine group, and this biocide can besimply added to the fluid used for pressure treating the wood.

One attempt to improve soluble copper containing wood preservatives wasto incorporate other salts. PCT patent application WO 92/19429,published Nov. 12, 1992, in Example 2, describes a method of treating anarticle of prepared wood by immersing it for 20 minutes in a bath of1800 C linseed oil containing a drying agent, or drier, of 0.07% lead,0.003% manganese and 0.004% calcium naphthenate, 0.3% coppernaphthenate, and 0.03 zinc naphthenates as an insecticide and fungicide.Others have tried alternative metal-compounds, including silver. None ofthese have found commercial acceptance.

Fojutowski, A.; Lewandowski, 0, Zesz. Probl. Postepow Nauk Roln. No.209: 197-204 (1978), describes fungicides comprising fatty acids withcopper compounds, applied by dipping hardboard heated to 1200 C into abath of the fungicide, also maintained at 1200 C. This is notpracticable for a variety of reasons. In “A New Approach To Non-Toxic,Wide-Spectrum, Ground-Contact Wood Preservatives, Part 1. Approach AndReaction Mechanisms,” HOLZFORSCHUNG Vol. 47, No. 3, 1993, pp. 253-260,it is asserted that copper soaps, made with the carboxylic acid groupsfrom unsaturated fatty acids of non-toxic vegetable oils, rosin, andfrom synthetic unsaturated polyester resins have effectiveness andlong-term durability as ground contact wood preservatives for useagainst termites and fungal attack. These are not yet in widespread use,and are expected to have high leach rates and the bio-available fattyacids are expected to encourage some molds.

The solubility of copper preservatives can be controlled by using, forexample, an oil barrier. But these oils can unfavorably change thecolor, appearance, and burning properties of the wood, and can be strongirritants. Oil-soaked wood containing oil-soluble biocides likechlorothalonil, e.g., utility poles, are highly resistant to leachingand biological attack, but the appearance of this wood is not acceptablefor most uses. Japanese Patent Application 08183,010 JP, published in1996, describes a modified wood claimed to have mildew-proofing andantiseptic properties and ant-proofing properties, made by treating woodwith a processing liquid containing a copper salt and linseed oil oranother liquid hardening composition. U.S. Pat. No. 3,837,875 describesas a composition for cleaning, sealing, preserving, protecting andbeautifying host materials such as wood a mixture of boiled linseed oil,turpentine, pine oil, a dryer and 28 parts per million of metalliccopper. Feist and Mraz, Forest Products Lab Madison Wis., WoodFinishing: Water Repellents and Water-Repellent Preservatives. Revision,Report Number-FSRN-FPL-0124-Rev (NTIS 1978) discloses preservativescontaining a substance that repels water (usually paraffin wax orrelated material), a resin or drying oil, and a solvent such asturpentine or mineral spirits. Addition of a preservative such as coppernaphthenate to the water repellent is asserted to protect wood surfacesagainst decay and mildew organisms. Soviet Union Patent No. SU 642166describes a wood surface staining and preservation treatment, carriedout by impregnating wood with an aqueous copper salt solution, followedby thermal treatment in boiling drying oil containing 8-hydroxyquinolinedye. U.S. published application 20030108759 describes injecting a copperammonium acetate complex and a drying oil as a wood preservative. Again,oil is not favored as it can alter burning characteristics of wood, canbe staining and/or discoloring, and can be an irritant. It is alsodifficult to work with and to inject into wood. None of the abovemethods of preserving wood have met commercial acceptance.

U.S. Pat. No. 6,521,288 describes adding certain organic biocides topolymeric nanoparticles (particles), and claims benefits including: 1)protecting the biocides during processing, 2) having an ability toincorporate water-insoluble biocides, 3) achieving a more evendistribution of the biocide than the prior art method of incorporatingsmall particles of the biocide into the wood, since the polymercomponent acts as a diluent, 4) reducing leaching with nanoparticles,and 5) protecting the biocide within the polymer from environmentaldegradation. The application states that the method is useful forbiocides including chlorinated hydrocarbons, organometallics,halogen-releasing compounds, metallic salts, organic sulfur compounds,and phenolics, and preferred embodiments include copper naphthenate,zinc naphthenate, quaternary ammonium salts, pentachlorophenol,tebuconazole, chlorothalonil, chlorpyrifos, isothiazolones,propiconazole, other triazoles, pyrethroids, and other insecticides,imidichloprid, oxine copper and the like, and also nanoparticles withvariable release rates that incorporate inorganic preservatives as boricacid, sodium borate salts, zinc borate, copper salts and zinc salts. Theonly examples used the organic biocides tebuconazole and chlorothalonilincorporated in polymeric nanoparticles. There is no enabling disclosurerelating to any metal salts. While data was presented showing efficacyof tebuconazole/polymeric nanoparticle formulations andchlorothalonil/polymeric nanoparticle formulations in wood, the efficacyof these treatments was not compared to those found when using othermethods of injecting the same biocide loading into wood. Efficacy/leachresistance data was presented on wood product material, where it wasfound that the nanoparticle/biocide treated wood had the same propertiesas the wood product treated with a solution of the biocide, i.e., thepolymeric nanoparticles had no effect. Finally, it is known in the artthat transport of preservative material is a large cost item, anddiluents will merely exacerbate this problem.

We have discussed the problems with current systems, e.g., they addundesired oil; they increase corrosion; they are dilute; they areexpensive, especially when the metal-based biocides must be combinedwith large quantities of organic biocides; the high copper leach ratesare both a serious environmental problem in itself and will almostcertainly decrease the longevity of treatment below that obtained withCCA. However, cost is a primary factor in the selection of a woodpreservative. The market is accustomed to the low cost and effectivenessof CCA, and the market is not ready to bear the incremental costs oflarge amounts of expensive biocides and other materials such aspolymeric nanoparticles.

SUMMARY OF THE INVENTION

The principal aspect of the invention is the copper-based particulatepreservative treatment for wood and wood products. One embodiment ofthis invention is an effective, long-lasting, environmentallyresponsible, non-staining/coloring, inexpensive, non-corrosion inducing,injectable, substantially crystalline (or amorphous sparingly soluble),copper-based particulate preservative treatment for wood and woodproducts that is substantially free of hazardous material. Yet anotherembodiment of the invention is an effective, long-lasting,environmentally responsible, non-staining/coloring, inexpensive,non-corrosion-inducing, injectable, substantially crystalline (oramorphous sparingly soluble), zinc-based particulate preservativetreatment for wood and wood products that is substantially free ofhazardous material. This zinc-based particulate composition can be usedindependently of the copper-based particulates, but in preferredembodiments is used in combination with one or more copper-basedparticulates. In preferred embodiments, the substantially crystalline(or amorphous sparingly soluble) copper- and/or zinc-based particulatesare injected in a formulation comprising one or more organic biocides.As used herein, the term “organic biocide” also includes organometallicbiocides.

One aspect of the present invention relates to a preservative that maybe used to preserve wood and wood products. In one embodiment, apreservative of the invention is a copper-based preservative. In apreferred embodiment, the copper-based preservative comprisescopper-based particles. Exemplary particles comprise, for example,copper hydroxide, a copper salt, and a copper oxide.

In one embodiment, the copper-based particles comprise a substantiallycrystalline copper compound. At least about 20%, 30%, 50%, or 75% of theweight of the copper-based particles may be composed of thesubstantially crystalline copper compound. In another embodiment,essentially all of the weight of the copper-based particles is composedof substantially crystalline copper compound. The substantiallycrystalline copper compound may comprise, for example, at least one ofcopper hydroxide (such as Cu(OH).sub.2), a copper salt, and a copperoxide (such as CuO).

Exemplary copper-based particles of the invention are sufficiently smallto be present within wood without a substantial reduction in theoriginal strength of the wood. For example, substantially all of thecopper-based particles may be sized to occupy pores or vesicles of wood.In one embodiment, wood or a wood product may be impregnated withcopper-based particles of the invention.

Copper or copper-based particles present within wood or wood products ispreferably less mobile than copper present in a liquid withoutcopper-based particles of the invention. Preferably, the copper-basedparticles are sufficiently insoluble so as to not be easily removed byleaching but are sufficiently soluble to exhibit toxicity to primaryorganisms primarily responsible for the decay of the wood. Exemplarycopper-based particles of the invention are sufficiently small to bepresent within wood without a substantial reduction in the originalstrength of the wood. For example, substantially all of the copper-basedparticles may be sized to occupy pores or vesicles of wood. In oneembodiment, exemplary wood preservatives comprise copper-based particleshaving a size distribution in which at least 50% of particles have adiameter smaller than 0.25 μm, 0.2 μm, or 0.15 μm. A preferred particlesizing technique is a sedimentation or centrifugation technique based onStoke's Law.

Another embodiment of this invention is an effective, long-lasting,environmentally responsible, non-staining/coloring, inexpensive,less-corrosion-inducing, injectable, sparingly soluble coppersalt-containing particulate preservative treatment for wood and woodproducts that is substantially free of hazardous material. Generally,crystalline salts are preferred because they have lower rates ofdissolution than do their amorphous analogs. However, amorphous saltsare equally effective, and particulates made from amorphous salts can betreated with one or more coatings, or can be made of a particular size,such that the amorphous material may easily have release and leachcharacteristics like the substantially crystalline salts. Substantiallycrystalline salts should be considered a preferred variant of theinvention, as the same disclosure is generally equally applicable toamorphous sparingly soluble copper salts, or substantially amorphoussparingly soluble copper salts. A “sparingly soluble salt” has, forexample, a K_(sp) less than about 1 E-8, preferably between about 1 E-IOto about 1 E-21.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent application file contains at least one drawing executed incolor. Copies of this patent application publication with the colordrawing will be provided by the Office upon request and payment of thenecessary fee.

FIG. 1 is a photograph of wood injected with the composition of thisinvention compared to wood injected by a prior art composition.

FIG. 2 is a graph demonstrating copper leaching data for selectedcompositions.

FIG. 3 is a photograph of a sliced interior section of wood block,untreated, treated at 0.22 pounds per cubic foot with injected coppersalt particulates, and treated and developed.

DETAILED DESCRIPTION OF THE INVENTION

The copper-based particulates can comprise or consist essentially of anysparingly soluble substantially crystalline (or sparingly solubleamorphous) copper salts. In one embodiment the substantially crystalline(or amorphous sparingly soluble) copper salts in the copper-basedparticulates comprise or consist essentially of one or more copper saltsselected from copper hydroxides; copper carbonates (e.g., “yellow”copper carbonate); basic (or “alkaline”) copper carbonates; basic coppersulfates including particularly tribasic copper sulfate; basic coppernitrates; copper oxychlorides (basic copper chlorides); copper borates;basic copper borates; copper ferricyanate; copper fluorosilicate; copperthiocyanate; copper diphosphate or copper pyrophosphate, copper cyanate;and mixtures thereof. In one embodiment, the copper based particlescomprise a substantially crystalline copper compound. At least about20%, 30%, 50%, or 75% of the weight of the copper-based particles may becomposed of the substantially crystalline copper compound(s).

In a preferred embodiment the substantially crystalline (or amorphoussparingly soluble) copper salts in the copper-based particulatescomprise or consist essentially of one or more copper salts selectedfrom copper hydroxides; copper carbonates, basic (or “alkaline”) coppercarbonates; basic copper sulfates including particularly tribasic coppersulfate; basic copper nitrates; copper oxychlorides (basic copperchlorides); copper borates, basic copper borates, and mixtures thereof.In one embodiment, the copper-based particles comprise a substantiallycrystalline copper compound. At least about 20%, 30%, 50%, or 75% of theweight of the copper-based particles may be composed of thesubstantially crystalline copper compound.

In another embodiment the substantially crystalline (or amorphoussparingly soluble) copper salts in the copper-based particulates in awood preservative formulation can comprise or consist essentially of aplurality of sparingly soluble substantially crystalline (or amorphoussparingly soluble) copper salts selected from copper oxide, copperhydroxides; copper carbonates, alkaline (or “basic”) copper carbonates;alkaline copper sulfates; alkaline copper nitrates; copper oxychlorides;copper borates, basic copper borates, and mixtures thereof, with theproviso that at least one of the substantially crystalline (or amorphoussparingly soluble) copper salts is not a copper oxide. Of the copperoxides, Cu₂O is preferred over CuO. In a variant of this, thecopper-based particulate material can comprise or consist essentially ofone or more sparingly soluble substantially crystalline copper saltsselected from copper hydroxides; copper carbonates, alkaline (or“basic”) copper carbonates; alkaline copper nitrates; alkaline coppersulfates; copper oxychlorides; copper borates, basic copper borates, andmixtures thereof. In one embodiment, the copper-based particles comprisea substantially crystalline copper compound. At least about 20%, 30%,50%, or 75% of the weight of the copper-based particles may be composedof the substantially crystalline copper compound(s).

In any of the above, the substantially crystalline (or amorphoussparingly soluble) copper composition can have a substantial amount ofone or more of magnesium, zinc, or both, wherein these cations areeither dispersed within the substantially crystalline (or amorphoussparingly soluble) copper composition or a separate phase within aparticulate. In preferred embodiments of the invention, at least someparticulates comprise copper hydroxide, basic copper carbonate, or both.In more preferred embodiments, the copper hydroxide comprises between 6and 20 parts of magnesium per 100 parts of copper, for example between 9and 15 parts of magnesium per 100 parts of copper. Alternatively, inanother more preferred embodiments, the copper hydroxide comprisesbetween 6 and 20 parts total of magnesium and zinc per 100 parts ofcopper, for example between 9 and 15 parts total of magnesium and zincper 100 parts of copper. In some embodiments, the basic copper carbonatecomprises between 6 and 20 parts of magnesium per 100 parts of copper,for example between 9 and 15 parts of magnesium per 100 parts of copper,or alternatively between 6 and 20 parts total of magnesium and zinc per100 parts of copper, for example between 9 and 15 parts total ofmagnesium and zinc per 100 parts of copper. Alternatively oradditionally, in a preferred embodiment, the copper hydroxide and/orbasic copper carbonate comprises between about 0.01 and about 5 parts ofphosphate per 100 parts of copper, for example between 9 and 15 parts ofphosphate per 100 parts of copper.

In another preferred embodiment, the slurry comprises sparingly solublecopper salt particulates and also comprises zinc borate particulates.Preferably, at least some of the sparingly soluble copper salt-basedparticulates comprise copper borate. It is known to use a two stageprocess where a zinc or copper salt is injected into the wood followedby a second step wherein the borax is injected and the insoluble metalborate is formed in situ. Such a complicated, time-consuming, andtherefore expensive process in not sufficiently cost-effective. As thesolubility of copper borate is very pH sensitive, in a preferredembodiment the sparingly soluble copper salts comprise an alkalinematerial, e.g., copper hydroxide or copper carbonate, to reduce thesolubility of the copper borate. The zinc borate loading can range from0.025% to 0.5%, for example, independent of the copper loading in thewood.

In any of the above-described embodiments, the substantially crystallinecopper composition in copper-based particulates and/or copper-basedparticulate material can further comprise one or more solublesubstantially crystalline copper salts, for example copper sulfate,copper fluoroborate; copper fluoride, or mixtures thereof, where thesoluble substantially crystalline copper salts phase is stabilizedagainst dissolution.

In any of the above-described embodiments, the substantially crystallinecopper composition in copper-based particulates and/or copper-basedparticulate material can further comprise the substantially insolublecopper salt copper phosphate, Cu₃(PO₄)₂. In any of the above-describedembodiments, the copper composition in copper-based particulates and/orcopper-based particulate material can further comprise the insolublecopper salt copper 8-quinolinolate. In any of the above-describedembodiments, the composition can further comprise copper quinaldate,copper oxime, or both in particulate form. If there are copper-basedparticulates substantially comprising Cu₃(PO₄)₂ and/or copper oxideand/or copper 8-quinolinolate, the particulates should be exceedinglysmall, e.g., less than about 0.07 microns, preferably less than about0.05 microns, to provide maximum surface area to help dissolution of theparticles, and the wood treatment should contain another type ofsubstantially crystalline (or amorphous sparingly soluble) copper-basedparticulates, e.g., basic copper carbonate, basic copper borate,tribasic copper sulfate, copper hydroxides, and the like.

The zinc analogs of the above are useful for the zinc-based particulatesof the alternate embodiments of the invention. In one embodiment thecopper-based particulate material can further comprise one or more ofcrystalline zinc salts selected from zinc hydroxide; zinc oxides; zinccarbonate; zinc oxychloride; zinc fluoroborate; zinc borate, zincfluoride, or mixture thereof. The zinc salts may be in a separate saltphase, or may be mixed CU/Zn salts, or combinations thereof. Inpreferred embodiments the particle comprises at least about 40%,preferably at least about 60%, and more preferably at least about 80% byweight of one or more substantially crystalline (or amorphous sparinglysoluble) copper salts, crystalline zinc salts, or mixtures orcombinations thereof.

In one embodiment the copper-based particulate preservative treatmentfor wood can further comprise zinc-based particulates comprising one ormore of crystalline zinc salts selected from zinc hydroxide; zincoxides; zinc carbonate; zinc oxychloride; zinc fluoroborate; zincborate, zinc fluoride, or mixture thereof. The preferred zinc-basedsubstantially crystalline material are zinc hydroxide, zinc borate, zinccarbonate, or mixture thereof, which may be doped with other cations,e.g., from 0.1 to 10% copper, from 0.1 to 10% magnesium, or both, forexample, based on the total weight of the cations in the substantiallycrystalline (or amorphous sparingly soluble) material. In preferredembodiments the particle comprises at least about 40%, preferably atleast about 60%, and more preferably at least about 80% by weight of oneor more crystalline zinc salts.

Preferred embodiments of the invention comprise particles comprising oneor more of copper hydroxide, alkaline copper carbonate, alkaline copperoxychloride, tribasic copper sulfate, copper borate, or mixturesthereof. The most preferred embodiments of the invention compriseparticles comprising copper hydroxide, alkaline copper carbonate, copperborate, alkaline copper borate, or mixtures thereof.

Metal salt-based preservatives require added organic biocides to havethe efficacy of the traditional CCA treatments. It is believed thatcertain organic biocides are very effective against most (but not all)undesired bio-organisms, and is also long-lasting. A principal functionof the copper in such a system is to inhibit growth of thosebio-organisms that degrade the organic biocides and/or that areresistant to the organic biocides. The most preferred embodiments ofthis invention have copper-based particulates and optionally one or moreof zinc-based particulates and tin-based particulates, and furthercomprise between about 0.01% to about 20% by weight total of one or moreorganic biocides. In addition, in some embodiments, the particulatesprovide a carrier to carry the organic biocides into the wood and helpensure the biocide is well-distributed throughout the wood. Preferredembodiments of the invention are an injectable copper-based particulatepreservative treatment for wood that further comprises one or moreinjectable organic biocides attached to particulates.

Other aspects of this invention include methods to prepare thecopper-based particulates, methods of formulating the injectable woodtreatment compositions that comprise the copper-based particulates andoptionally one or more organic biocides, methods of transporting theinjectable wood treatments, methods of mixing and injecting thecopper-based particulate wood preservative composition, and also woodand wood products treated with the copper-based particulate preservativetreatment compositions.

We believe our combination of manufacture, pretreatment, formulation andinjection into wood of basic (“sparingly soluble”) crystalline coppercompounds injected as particulates represent a significant discovery.The slurries of this invention are essentially unaffected by the use ofhard water in the application. The CMC material used in the prior artprecipitates an objectionable residue of calcium and magnesiumcarbonates onto the surface of the wood. Injection of the presentformulation uses the standard operating procedure that is commonlypracticed in the industry. No changes are needed. The presentformulation eliminates the nitrogen content of the prior art products;and we believe the nitrogen is associated with the enhanced rate ofsapstain growth which presently necessitates the use of expensivesapstain control agents. Removal of the fraction of particles having adiameter greater than 1 micron (1000 nanometers), accomplished with acomponent of this technology, means the slurries are stable—slurryparticles settle over the course of days or even weeks. This is adesirable application feature. The copper should be relativelynon-leachable, being comparable with the rates associated with the CCAproducts. Due to lower leach rates, the product should be usableunderground, near waterways, and also in marine applications. The costper pound of copper is estimated to be between $0.20 to $0.50 less thanpresent copper-MEA-carbonate products. We believe that corrosivity ofthe product will be less than that associated with thecopper-MEA-carbonate products. Freight should be only one third thatassociated with the copper-MEA-carbonate products.

Unless otherwise specified, all compositions are given in “percent”,where the percent is the percent by weight based on the total weight ofthe entire component, e.g., of the particle, or to the injectablecomposition. In the event a composition is defined in “parts” of variouscomponents, this is parts by weight, wherein the total number of partsin the composition is between 90 and 110.

Effective—By “effective” we mean the preservative treatment issufficiently distributable through the wood product, and is sufficientlysoluble and available so as to provide a bio-active concentration ofcopper ions in the wood matrix. By “bio-active” we mean the preservativetreatment is sufficiently biocidal to one or more of fungus, mold,insects, and other undesired organisms which are normally the target ofcopper-containing wood preservatives such that these organisms avoidand/or can not thrive in the treated wood: It is known that copperarsenate (Cu₃(AsO₄)₂) injected as a molecular layer is an effectivebiocide. Therefore, the particulate preservative treatment shouldprovide a copper concentration roughly similar (for example, about thesame to about two times as high) as that provided by the chromatedcopper arsenate (CCA) treatment. Too low a solubility, and the copper isnot bioactive. At the same time, the injectable copper-based woodpreservative treatment of this invention is intended to have one or moreorganic-based biocides incorporated therewith in amounts the same as arecurrently being used with soluble copper preservatives, and efficacy isbased on the combination of the copper (and/or zinc) component incombination with the organic biocides.

Long-lasting—By “long-lasting” we mean the preservative treatment has aneffective life of at least about the same as a traditional CCA-treatedproduct, alternatively, the treatment lasts at least about 20 yearsunder normal outdoor ground-contact use, for example. Too high asolubility of the particulates, and the copper is leached out of thewood at too fast a rate. Such fast leaching creates environmentalproblems, i.e., the leached copper contaminates the environment, andalso longevity problems, i.e., so much copper may be leached from thewood that the remaining treatment can no longer provide a bio-activeconcentration of copper ions.

Leaching is a function of particle size and the solubility of thesubstantially crystalline (or amorphous sparingly soluble)copper-containing material. Larger size particles have lower leachrates, while particles in a size range from 1 to 10 nanometers undercertain circumstances will not have a leach rate much different thanthat of an injected copper salt solution. In preferred embodiments ofthis invention, at least 50% by weight of the copper-containingparticulates have a size greater than 40 nanometers. In more preferredembodiments, at least 50% by weight of the copper-containingparticulates have a size greater than 80 nanometers. In one preferredembodiment, at least 80% by weight of the copper-containing particulateshave a size between 0.05 microns and 0.4 microns.

Leaching is not the only mechanism whereby material can be flushed fromwood. Because the material is in particulate form, there is apossibility that particulates will be flushed from the wood. Evidencesuggests that very small substantially spherical nanoparticles, i.e.,spherical particles of size 5 to 20 nanometers, can migrate freelythrough a wood matrix. United States Patent Application 20030077219teaches a variant of the precipitation method of forming nanoparticlesfrom micro-emulsions, the invention apparently relating to a blockpolymer used to stabilize the micro-emulsions. This publication claimsthat nanoparticles penetrate more easily and more deeply into the woodlayers under treatment due to their “quasi atomic size,” thuseliminating or reducing the need for pressure impregnation. Immersion ofwood into a copper hydroxide micro-emulsion showed the copper hydroxidepenetrated to a depth of more than 10 to 298 mm. However, while saidparticles are easy to inject, they are also clearly easily transportedthrough wood and would be easily flushed from the wood. These woodpreservative treatments would not be long-lasting. Therefore, inpreferred embodiments of the invention the material is substantiallyfree of substantially spherical particulates, wherein the size of thespherical particulates is less than about 20 nanometers, particularlyless than 15 nanometers.

Generally, the leaching rate from dispersed particulates is controlledby 1) diffusion and boundary layer effects around the limited surfacearea available to water; 2) the activation energy needed to disrupt thecrystal and to thereby cause dissolution, and 3) the absolute solubilityof the material. Solubility is not an easy parameter to control; thesolubility of copper itself in compositions containing hydroxyl groupsand carbonates is about 0.01 ppm at pH 10, 2 ppm at pH 7, but is 640 ppmat pH 4. Wood itself has a “pH” between 4 and 5, but there isessentially no buffering capacity. Therefore, copper hydroxides are acomponent of the preferred substantially crystalline (or amorphoussparingly soluble) copper material, as the hydroxides will raise the pHof the water in the wood.

Leaching will be discussed extensively infra Advantageously, theparticulates of the present invention provide at 240 hours into an AWPAE11-97 leach test a total leached copper value that is within a factorof two above, to within a factor of five below, preferably within afactor of three below, the total leached copper value obtained by a woodsample treated with CCA and subjected to the same test.

Substantially free of hazardous material—By “substantially free ofhazardous material” we mean the preservative treatment is substantiallyfree of materials such as lead, arsenic, chromium, and the like. Bysubstantially free of lead we mean less than 0.1% by weight, preferablyless than 0.01% by weight, more preferably less than 0.001% by weight,based on the dry weight of the wood preservative. By substantially freeof arsenic we mean less than 5% by weight, preferably less than 1% byweight, more preferably less than 0.1% by weight, for example less than0.01% by weight, based on the dry weight of the wood preservative. Bysubstantially free of chromium we mean less than 0.5% by weight,preferably less than 0.1% by weight, more preferably less than 0.01% byweight, based on the dry weight of the wood preservative.

Environmentally responsible—By “environmentally responsible” we mean thewood preservative (including co-biocide) has a bioactive effectivenessthat is at least about one half that of CCA, preferably at least threequarters of that of CCA, for example, about equal to that of CCA, forspecified organism based on the weight percent of the wood preservativematerial in the wood. If, for instance, the wood preservative has abioactive effectiveness equal to that of CCA, then wood treated with aselected concentration of the wood preservative will have substantiallysimilar bioactivity as wood treated with the same concentration of CCA.

Additionally, the environmentally responsible material is substantiallyfree of small nanoparticles which can be readily flushed from wood.Therefore, in preferred embodiments of the invention the environmentallyresponsible material is substantially free of substantially sphericalparticulates, wherein the size of the spherical particulates is lessthan about 20 nanometers, particularly less than 5 nanometers. Morepreferably, in preferred embodiments of the invention theenvironmentally responsible material is substantially free ofparticulates having a size less than about 20 nanometers, particularlyless than 5 nanometers. Nanoparticle-sized metal particulates may betoxic to certain aquatic life, though the data is very preliminary.

Additionally, environmentally responsible wood preservatives arebeneficially substantially free of organic solvents. By substantiallyfree we mean the treatment comprises less than 10% organic solvents,preferably less than 5% organic solvents, more preferably less than 1%organic solvents, for example free of organic solvents, based on theweight of the copper in the wood preservative.

Injectable—By “injectable” we mean the wood preservative particulatesare able to be pressure-injected into wood, wood products, and the liketo depths normally required in the industry, using equipment, pressures,exposure times, and procedures that are the same or that aresubstantially similar to those currently used in industry. Pressuretreatment is a process performed in a closed cylinder that ispressurized, forcing the chemicals into the wood. Copper loading, alsocalled copper retention is a measure of the amount of preservative thatremains in the wood after the pressure is released. It is given as“pcf,” or pounds of preservative per cubic foot of wood. Retentionlevels that must be reached are dependent on three variables: the typeof wood used, the type of preservative used, and the use of the woodafter treatment. The sparingly soluble copper-salt particulates of thisinvention are typically expected to be added to wood in an amount equalto or less than 0.25 pounds as copper per cubic foot. In preferredembodiments of the invention incising is not expected to be required toinject the slurries of the present invention into lumber havingthicknesses of 6 to 10 inches.

Injectability requires the particulates be substantially free of thesize and morphology. that will tend to accumulate and form a filtercake, generally on or near the surface of the wood, that results inundesirable accumulations on wood in one or more outer portions of thewood and a deficiency in an inner portion of the wood. Injectability isgenerally a function of the wood itself, as well as the particle size,particle morphology, particle concentration, and the particle sizedistribution.

The requirements of injectability for substantially round, e.g., thediameter is one direction is within a factor of two of the diametermeasured in a different direction, rigid particles generally are 1) thatsubstantially all the particles, e.g., greater than 98% by weight, havea particle size with diameter equal to or less than about 0.5 microns,preferably equal to or less than about 0.3 microns, for example equal toor less than about 0.2 microns, and 2) that substantially no particles,e.g., less than 0.5% by weight, have a diameter greater than about 1.5microns, or an average diameter greater than about 1 micron, forexample. We believe the first criteria primarily addresses the phenomenaof bridging and subsequent plugging of pore throats, and the secondcriteria addresses the phenomena of forming a filter cake. Once a porethroat is partially plugged, complete plugging and undesired buildupgenerally quickly ensues.

However, there are minimum preferred particulate diameters for the woodtreatment, which depend somewhat on the copper salt(s) that are in theparticulates. If the salts have a high solubility, very smallparticulates having a large surface to mass ratio will result in toohigh a copper ion concentration, and too fast a copper leaching,compared to preferred embodiments of this invention. Further, very smallparticulates, especially for example small spherical particles ofdiameter between about 0.003 to about 0.02 microns, are readily flushedfrom the wood. Generally, it is preferred that at least 80% by weight ofthe particles be above 0.01 microns in diameter, preferably greater than0.03 microns, for example greater than 0.06 microns in diameter.

By injectable, unless otherwise specified, we mean injectable intonormal southern pine lumber. This invention also encompasses injectingthe particulates into other woods as well as into for example heartwood.Selected other woods and heartwood may require a smaller substantiallylower criteria on particle dimensions for injectability, and suchformulations can be made as discussed herein, but the formulation mostof interest is a commercially operative formulation developed for normalSouthern Pine. Such a formulation will typically be useful for all otherwoods, with the possible exception of selected heartwood. Such problemswith heartwood are normally not a substantial concern, as the injectedparticulate material may form a partial protective filter cake aroundheartwood that protects the heartwood without causing unsightlyaccumulations of preservative on the wood, and also heartwood isnaturally substantially resistant to attack by many bioorganisms andtherefore may require less copper to constitute sufficient protection.

We have found three methods to improve injectability and/or to maintaininjectability of particulates. These methods improve particle sizedistribution and/or morphology by wet milling, and chemically andphysically stabilize the particulates by coating the particulates withselected materials.

Non-staining/Non-coloring—By “non-staining/non-coloring” we mean thewood preservative does not impart undesired color to the wood. Largeparticulates, or large agglomerations of smaller particulates, impose avisible and undesired color to the treated wood, which is generallybluish or greenish. Surprisingly, coloring is usually indicative of poorinjectability. Individual particles of diameter less than about 1micron, preferably less than 0.5 microns, that are widely dispersed in amatrix do not color a wood product to any substantial degree. Filtercake forms unsightly coloring. An aggregation of particles, similar tofilter-cake, could contribute un-wanted color. Preferably 100% by weightof the particles have an average diameter of less than 1 micron, wherean average diameter is the diameter measured by Stokes law settling(which may be assisted by centrifugation), or by preferably by dynamiclight (X-ray) scattering or by Doppler light scattering. Evenparticulates having a size greater than 0.5 microns can impart veryvisible color, and agglomerates of similar size have the same effect asdo large particles. In a preferred embodiment of the invention, at leastabout 95%, e.g., at least about 99% by weight of theparticulates/aggregates are smaller than 0.5 microns in averagediameter. More preferably, at least about 95%, e.g., at least about 99%by weight of the particulates/aggregates are smaller than 0.35 micronsin average diameter. Even more preferably, at least about 95%, e.g., atleast about 99% by weight of the particulates/aggregates are smallerthan 0.3 microns in average diameter. Generally, it is preferred that atleast 90% by weight of the particles be above 0.01 microns in diameter,preferably greater than 0.03 microns, for example greater than 0.06microns. Certain compounds, particularly basic copper carbonate, copperhydroxide, and copper oxychloride are preferred because they impart lesscolor than do other particles of comparable size. Additionally, thepresence of a zinc salt, a magnesium salt, or both either as a separatephase or as a mixed phase may also reduce color.

Inexpensive—By “inexpensive” we mean the wood preservative is preparedusing techniques so that the cost of the wood treatment is competitivewith, for example, copper-ethanolamine-complex treatments and othercommonly used treatments. As the cost of copper is substantiallyconstant regardless of the source, inexpensive relates primarily to thecosts of manufacture, separation, sizing, and preservation of theparticulate material. There are many techniques to create very smallnanoparticles, but most of these processes are far too costly to beuseful in the mass production of a copper-based wood preservativetreatment. Generally, the term “inexpensive” means at a processed costless than or equal to the current costs of the soluble copper-co-biocidetreatments, alternately within about 20% of the cost of prior art CCAtreatments.

The preferred method of production is a precipitation process, in theabsence of organic solvents and the like. Preferably the reactants areof standard industrial quality, as opposed to higher levels of purity.The particles start with certain characteristics including sizedistribution and morphology, e.g., at least 2% by weight of theparticles have a diameter greater than 1 micron, usually greater than1.5 microns, and generally must undergo subsequent treatment, e.g.,milling, to make sure the particle size and particle size distributionare favorable for injection. Particles made by other processes,particularly emulsion precipitation processes and fuming processes, arenot sufficiently cost effective to manufacture commercially acceptablecopper particulates for wood preservation.

It is known that nanoparticles can be formed for example bymicro-emulsion (or micelle) precipitation, and the like. The micellesystem, where emulsions of small and uniformly sized micelles are usedas nanoreactors in which the deposition of the metal salt is carriedout, are known in the art. For example, it is known to make nickel andnickel/copper (7/3) carbonate particles via water in oil(hexane/hexanol) microemulsions. Two separate microemulsions with themetal salt and ammonium bicarbonate, respectively, were prepared andmixed rapidly to form metal carbonate nanoparticles of 6 to 7 nmdiameter with a small diameter distribution. Such processes, whileuseful in forming very small particulates, are not useful in formingcommercially acceptable wood preservative. The associated costs ofadding and removing the solvents used to form the emulsions makes theseprocesses economically un-usable for the purpose of forming acopper-containing injectable particulate wood preservation material.

It is known that nanoparticles can be formed for example by formingfumed copper salts via a vapor process or an aerosol oxidation process.The authors of Copper and Copper Oxide Nanoparticle Formation byChemical Vapor Nucleation From Copper (II) Acetylacetonate by Albert G.Nasibulin, P. Petri Ahonen, Olivier Richard, Esko I describe methods offorming e.g., 2 nm to 20 nm in diameter nanoparticles. Generally, fumingprocesses are limited to producing the oxides of copper, as theseauthors produced. Again, the cost of obtaining such small size (andnarrow particle distribution) is not justified by any increase inefficacy of the particles for most copper salts of this invention.

The cost of polymeric nanoparticles to act as a carrier for the coppersalts is similarly not justifiable.

Less-Corrosion-Inducing—The commercial soluble copper containing woodpreservatives often result in increased metal corrosion, for example ofnails within the wood. Preserved wood products are often used inload-bearing out-door structures such as decks. Traditional fasteningmaterial, including aluminum and standard galvanized fittings, are notsuitable for use with wood treated with these new preservatives. Manyregions are now specifying that hardware, e.g., fittings, nails, screws,and fasteners, be either galvanized with 1.85 ounces zinc per squarefoot (a G-185 coating) or require Type 304 stainless steel. Generally,the presence of any salt will induce corrosion. By“less-corrosion-inducing” we mean the wood preservative has a reducedtendency, compared to a similar concentration of copper obtained fromthe soluble copper treatments such as the amine-copper-complextreatments and alkanolamine-copper-complex treatments in use today, tocorrode metal that contacts the wood. The degree of corrosion willdepend in large part on the salts selected, as well as on adjuvants, inparticular amines.

We believe that the amines present in the treatments used in solublecopper treatments—alkanolamines, ammonia, and the like—are corrosive tometals. We also believe that another problem with the new solublecomplexed copper preservatives is that they are, or they eventually turninto, biodegradable material that can encourage certain biologicalattacks, particularly mildew. The commonly used soluble copper compoundsprovide nitrogen-containing nutrients (amines) which are believed to actas food-stuff and causes an increase in the presence of sapstain molds,therefore requiring additional biocides effective on sapstain molds tobe added to protect the external appearance of the wood. When there isalso bio-available carbon sources, in addition to bio-availablenitrogen, the problem is made worse. Advantageously, the woodpreservative is substantially free of any amines other than certainselected amines that may be used as a supplemental biocide. Bysubstantially free we mean the treatment comprises less than 10% amines,preferably less than 5% amines, more preferably less than 1% amines, forexample free of amines, based on the weight of the copper in the woodpreservative. Alternatively, the term means there is less than one aminemolecule or moiety per four copper atoms, preferably less than one aminemolecule or moiety per ten copper atoms. Again, amines that are used assupplemental biocides, if any, are excluded from this limitation. Whilebasic copper nitrate is a useful sparingly soluble copper salt for usein this invention, in most embodiments of the invention the woodpreservative is also substantially free of nitrates.

In other embodiments of the invention an injectable copper-basedparticulate preservative treatment for wood that is substantially freeof bio-available nitrogen, and even more preferably substantially freeof bio-available nitrogen and bio-available carbon is provided. Bysubstantially free of bio-available nitrogen we mean the treatmentcomprises less than 10% of nitrates and organic nitrogen, preferablyless than 5% of nitrates and organic nitrogen, more preferably less than1% of nitrates and organic nitrogen, for example less than 0.1% ofnitrates and organic nitrogen, based on the weight of the copper in thewood preservative. In most of the soluble or complexed coppertreatments, there are between 1 and 4 atoms of organic nitrogen that actas a complexer or carrier for one atom of copper. In the preferredembodiments of this invention, there is less than 0.3 atoms, preferablyless than 0.1 atoms, for example less than 0.05 atoms of organicnitrogen per atom of copper in the wood preservative treatment. Again,organic nitrogen-containing compounds that are used specifically assupplemental biocides are excluded from this limitation. Bysubstantially free of bio-available carbon we mean the treatmentcomprises less than 30% of bio-available organic material (defined asmaterial that is degradable or that will during the lifespan of thetreatment will become degradable), preferably less than 10% ofbio-available organic material, more preferably less than 1% ofbio-available organic material, based on the weight of the copper in thewood preservative. Again, organic compounds that are used assupplemental biocides, if any, are excluded from this limitation. It isbelieved that the presence of bio-available organic carbon may encouragethe growth of certain molds.

In one embodiment, the copper-based particles are substantially free ofpolymers, such as organic polymers. For example, copper-based particlesof the invention may be substantially free of one or more ofpolyvinylpyridine, polymethacrylate, polystyrene,polyvinylpyridine/styrene copolymers, polyesters, polyethylene,polypropylene, polyvinylchloride, blends of the above homopolymers withacrylic acid and the like. By substantially free, it is meant that thecopper-based particles are less than about 50% by weight polymer. Thecopper-based particles may be less than about 35% by weight polymer, forexample, less than 25% by weight polymer, such as less than 15% byweight polymer. In one embodiment, the copper-based particles areessentially free of polymer, by which it is meant the copper-basedparticles comprise less than about 5% by weight polymer. In oneembodiment, the copper-based particles comprise less than about 2.5% byweight polymer. In one embodiment, the copper-based particles are freeof polymer.

In one embodiment of the invention, the copper-based particles maycomprise a polymer. In this embodiment, the ratio of the weight ofcopper present in the particles to polymer present in the particles maybe at least about 1 to 1, for example at least about 2 to 1, 4 to 1, 5to 1, 7 to 1, or at least about 10 to 1. For example, if ratio of theweight of copper present in the particles to the weight of polymerpresent in the particles is at least about 2 to 1, the particlescomprise at least about twice as much copper by weight as polymer.

Substantially crystalline—By “substantially crystalline” we mean, forexample, greater than about 30%, preferably greater than about 50%, byweight of the material of interest (copper salt, zinc salt, and thelike) is crystalline. A material is substantially crystalline if thematerial gives the distinctive X-ray diffraction patterns of thecrystalline entity (relating to d spacing, not present in the amorphousmaterial). A convenient technique for assessing the crystallinityrelative to the crystallinity of known crystalline salts is thecomparison of the relative intensities of the peaks of their respectiveX-ray powder diffraction patterns. The degree of crystallinity can bedetermined by, for example, determining the sum of the X-ray diffractionpeak heights (for the same sample size), in terms of arbitrary unitsabove background, and comparing the summed peak heights of thesubstantially crystalline material in, for example, the copper-basedparticulates with the corresponding peak heights of the knowncrystalline material. This procedure utilizes, for example, only thestrongest 4 peaks. When, for example, the numerical sum of the peakheights of the material in a particulate is 30 percent of the value ofthe sum of the peak heights of the same known crystalline copper salt,then the product is 30 percent crystalline and is substantiallycrystalline. The preferred method for determining crystallinity is bycalorimetry, by measuring the heat of dissolution of the sample in asolvent and comparing this heat with the measured heats of amorphous andcrystalline standard of the same salt, provided the dissolution of thecrystalline salt is substantially different than the dissolution of thecorresponding amorphous salt.

As crystallinity is difficult to measure, the following exemplarycompounds meet the requirements for substantially crystalline coppercompounds: copper(II) borate; copper boride (Cu₃B₂); yellow copper(I)carbonate; basic copper carbonate; copper(II) carbonate dihydroxide(CuCO₃×Cu(OH)₂); copper(II) carbonate dihydroxide (2CuCO₃×Cu(OH)₂);copper (I and II) chloride; copper(II) chloride×2H₂O; copper oxychloride(CuCl₂×Cu(OH₂); copper(I and II) cyanide; copper(I and II) fluoride;copper(II) formate; copper(I and II) oxide; copper phosphate×3 water;copper(I and II) sulfate; tribasic copper sulfate; and copper(I)thiocyanate. The term (I and II) means the copper(I) salt and thecopper(II) salt. These salts are considered substantially crystallinewith as much as 20% by weight based on the weight of the copper beingsubstituted with magnesium, zinc, or both. The following exemplarycompounds meet the requirements for substantially crystalline zinccompounds: zinc carbonate; zinc chloride; zinc cyanide; zincdiphosphate; zinc fluoride; zinc fluoride×4 water; zinc hydroxide; zincoxide; zinc phosphate; and zinc sulfate. These salts are typicallysubstantially crystalline with as much as 20% by weight based on theweight of the zinc being substituted with magnesium, copper, or both.The following exemplary compounds meet the requirements forsubstantially crystalline tin compounds: tin(II) chloride; tin(II)chloride×2 water; tin(II and IV) oxide; tin(II) diphosphate(pyrophosphate); tin(II) phosphate (Sn₃(PO₄)₂); and tin(II) sulfate.

In preferred embodiments, at least about 20%, 30%, 50%, or 75% of theweight of the copper-based particles may be composed of thesubstantially crystalline (or amorphous sparingly soluble) coppercompound. The substantially crystalline (or amorphous sparingly soluble)copper compound may comprise, and in preferred embodiments doescomprise, one or more cations in addition to copper, for example,magnesium and/or zinc. In another embodiment, essentially all of theweight of the copper-based particles is composed of substantiallycrystalline (or amorphous sparingly soluble) copper compound.

Several of the copper salts described herein are available incrystalline and in amorphous phases. Generally crystallinity ispreferred, as the lattice energy of the crystal is expected to slow downdissolution. However, amorphous copper salts are useful in theinvention, and for the less soluble salts the amorphous phases may bepreferred over crystalline phases. Phosphate-stabilized copperhydroxide, a preferred sparingly soluble copper salt used in embodimentsof this invention, is typically substantially amorphous. One embodimentof this invention is an effective, long-lasting, environmentallyresponsible, non-staining/coloring, inexpensive, non-corrosion-inducing,injectable, amorphous or substantially amorphous copper based,zinc-based, or tin-based particulate preservative treatment for wood andwood products that is substantially free of hazardous material.Amorphous sparingly soluble salts are equally effective, and they can betreated with one or more coatings, or can be made of a particular size,or of more insoluble salts, such that the amorphous material may easilyhave release and leach characteristics like the substantiallycrystalline salts. Substantially crystalline sparingly soluble saltsshould be considered a preferred variant of the invention, as the samedisclosure is generally equally applicable to amorphous material, orsubstantially amorphous material.

Copper-Based Particulate—As used herein, the term “copper-basedparticulate” means a particle having a size between about 0.7 micronsand about 0.01 microns that comprises at least one substantiallycrystalline (or amorphous sparingly soluble) copper salt. The term“particle” is used interchangably with the term “particulate,” while theterm “nanoparticle” refers to particles having a size less than about0.01 microns in diameter. The term “copper” includes, unlessspecifically stated otherwise, the cuprous ion, the cupric ion, ormixtures thereof, or combinations thereof. The term “copper-based” meansthe particle comprises at least about 20%, 30%, 50%, or 75% by weight ofone or more substantially crystalline (or amorphous sparingly soluble)copper compounds. In another embodiment, essentially all (e.g., morethan 95%) of the weight of the copper-based particles is composed ofsubstantially crystalline (or amorphous sparingly soluble) coppercompound.

Zinc-Based Particulate—As used herein, the term “zinc-based particulate”means a particle having a size between about 0.5 microns and about 0.01microns that comprises at least one substantially crystalline (oramorphous sparingly soluble) copper salt. The term “particle” is usedinterchangably with the term “particulate.” The term “zinc-based” meansthe particle comprises at least about 20%, 30%, 50%, or 75% by weight ofone or more substantially crystalline (or amorphous sparingly soluble)zinc compounds. In another embodiment, essentially all (e.g., more than95%) of the weight of the zinc-based particles is composed of one ormore substantially crystalline (or amorphous sparingly soluble) zinccompounds. The preferred substantially crystalline zinc-containingmaterials are zinc hydroxide, zinc borate (Zn(BO₂)₂×H₂O), and zinccarbonate. As for the copper-based particles and the tin-basedparticles, if the borate is used as the anion, preferably thecomposition also comprises one or more salts of carbonate or hydroxide(or hydroxide-containing) salts to maintain a slightly elevated pHwithin the wood matrix, to slow dissolution of the borate salts. Ifzinc-based particulates are used, they are advantageously used withcopper-based particulates.

Tin-based particulate—As used herein, the term “tin-based particulate”means a particle having a size between about 0.5 microns and about 0.01microns that comprises at least one substantially crystalline (oramorphous sparingly soluble) tin salt. The term “particle” is usedinterchangably with the term “particulate.” The term “tin-based” meansthe particle comprises at least about 20%, 30%, 50%, or 75% by weight ofone or more substantially crystalline (or amorphous sparingly soluble)tin compounds. In another embodiment, essentially all (e.g., more than95%) of the weight of the tin-based particles is composed of one or moresubstantially crystalline (or amorphous sparingly soluble) tincompounds. Generally, tin-based particulates are not preferred becausetin does not have the desired bio-activity. Tin oxides are believed tobe particularly inert, though Nanophase Technologies in February 2004claimed, in “Nanotechnology in brief” making pilot quantities of 30 nmsilver-doped nanocrystalline tin oxide for use in wood preservatives,speciality paints, polymer additives, conductive coatings, andelectronic materials. The preferred substantially crystalline tinmaterial are tin hydroxides, Sn(OH)₂ and Sn(OH)₄. If tin-basedparticulates are used, they are advantageously used with copper-basedparticulates.

It is recognized that some embodiments encompassed by this invention maynot meet all of the objects or characteristics of the preferredembodiments of the invention as described above. In preferredembodiments of the invention, the injectable material will meet any andpreferably most of the criteria listed above for the effective,long-lasting, environmentally responsible, non-staining/coloring,inexpensive, non-corrosion-inducing, injectable, substantiallycrystalline (or amorphous sparingly soluble), copper-based particulatepreservative treatment for wood and wood products that is substantiallyfree of hazardous material.

In preferred embodiments of the invention, the injectable copper-basedparticulates will meet any and preferably most of the criteria listedabove for the effective, long-lasting, environmentally responsible,non-staining/coloring, inexpensive, less-corrosion-inducing, injectable,substantially crystalline (or amorphous sparingly soluble), copper-basedparticulate preservative treatment for wood and wood products that issubstantially free of hazardous material.

The Substantially Crystalline Copper Composition in the Copper-BasedParticulates.

The copper-based particulates can have a substantially homogenoussubstantially crystalline (or amorphous sparingly soluble) coppercomposition within each particle. Alternatively, the particles cancomprise two or more separate substantially crystalline (or amorphoussparingly soluble) copper phases. Preferred particles comprise at least30%, preferably at least 50%, more preferably at least 70%, for examplebetween about 80% and about 98% by weight of total of copper hydroxides,copper oxides, basic copper carbonates, copper carbonates, copperoxychloride, tribasic copper sulfate, alkaline copper nitrate, copperborate, or mixtures thereof. Most comprise a basic copper salt, with theexception of copper borate and copper oxides. As a high pH suppressesthe solubility of copper borate, advantageously, treatments thatcomprise particulates of copper borate also comprise a basicsubstantially crystalline (or amorphous sparingly soluble)copper-containing salts. Copper carbonate is a most preferred compound,as it is less visible than some other salts, and has excellentsolubility characteristics.

In another embodiment of the invention, the various particles within awood preservative can comprise different substantially crystalline (oramorphous sparingly soluble) copper compositions. For example, atreatment may contain particles that comprise crystalline copper borate,other particles that comprise alkaline copper carbonate, and even otherparticles that comprise copper oxide. The particles having differentphases may in preferred embodiments be of different sizes, porosity, ormorphology, depending on the crystalline copper material present.

In one embodiment, exemplary wood preservatives comprise copper-basedsalt particles having a size distribution in which at least 50% ofparticles have a diameter smaller than 0.5 μm, 0.25 μm, 0.2 μm, or 0.15μm. A preferred particle sizing technique is a sedimentation orcentrifugation technique based on Stoke's Law. An exemplary preservativeof the invention comprises particles comprising a sparingly solublecopper salt, e.g., copper hydroxide, having an average particle diameterof less than about 500 nanometers, for example less than about 250nanometers, or less than about 200 nanometers. In one embodiment, theaverage particle diameter is at least 25 nanometers, for example, atleast 50 nanometers.

Method of Manufacture of Substantially Crystalline Copper-ContainingParticles

Exemplary copper-based particles comprise one or more of copper metal, acopper oxide, a copper hydroxide, copper carbonate, and a copper saltthat is sparingly soluble. Preferred wood preservatives comprisecopper-based particles that comprise at least about 20%, for example, atleast about 50%, 60%, 70%, or 75% by weight copper, based on the weightof the particle. An exemplary copper-based particle comprises abouttwice as much copper by weight as oxygen.

There are a large number of references describing how to makecopper-containing “nanoparticles.” These references generally can not beused to manufacture the particulates at the desired cost. The formationof 7 nanometer particles of any of CuO, Cu₂O, or mixed phase CuO/Cu₂O isdescribed for example in “Copper and Copper Oxide Nanoparticle Formationby Chemical Vapor Nucleation From Copper(II) Acetacetonate” wasdescribed in Journal of Nanoparticle Research, 3(5-6): 383-398, December2001. Such particles are, or course, readily injectable into wood, andif injected they may provide a degree of biological activity. But theycan not be used for the process because such particles are too expensivefor use in wood treatment. R. L. Hamilton and O. K. Cosser describedusing 35 nm CuO or 10 nm Cu metal particles to enhance thermalconductivity of antifreeze in “Thermal Conductivity of HeterogenousTwo-Component Systems”, Ind. & Engr. Chem. Fund., 1, 187-191 (1962).Such particles would also be expected to be injectable into wood. UnitedStates Patent Application 20030077219 describes a method for producingcopper salts from at least one cupriferous reactant and one additionalreactant, where micro-emulsions are prepared from two reactants whileemploying at least one block polymer to obtain intermediate productswith a particle size of less than 50 nm, preferably 5 to 20 nm. Materialcan be adjusted to specific applications through the appropriate dopingof foreign ions. This application teaches wood treatment applications,stating copper compounds that have been produced pursuant to the presentinvention can penetrate more easily and more deeply into the wood layersunder treatment due to their quasi atomic size. These improvedproperties can eliminate or reduce the need for pressure impregnationwhile ensuring prolonged protection against various organisms.Agglomerates characterized by a size of about 200 nanometers consist ofa multitude of primary particles characterized by a size range of 5 to20 nm. Example particle sizes were between 10 and 50 nm and agglomeratesizes between 100 and 300 nm. During the immersion of equivalent woodinto the copper hydroxide micro-emulsion prepared pursuant to theinvention, the copper hydroxide was not limited to the surface, butinstead penetrated to a depth of more than 10 to 298 mm. The use ofsolvents makes such processes generally too expensive for use in woodpreservatives, though this process can be useful provided the solventserves a subsequent purpose of solvating one or more organic biocides,to partially bind the organic biocides to the particulate by partiallyor completely removing the solvent by evaporation. Modifying the processof this application to make particulates greater than 50 nanometers indiameter, for example between about 100 and about 200 nanometers indiameter, can be useful provided the solvent serves a subsequent purposeof solvating one or more organic biocides, to partially bind the organicbiocides to the particulate by partially or completely removing thesolvent by evaporation.

The method of U.S. Pat. No. 6,596,246 which requires rigorous removal ofiron to make a copper hydroxide can be utilized. Such a processincreases the cost of the product, however.

In one embodiment of the invention, copper-based particles are prepared,such as by precipitation, from a mixture comprising copper and an amine.The copper and amine may be present in the form of a copper-aminecomplex. The mixture may comprise at least one of coppermonoethanolamine, copper diethanolamine, copper-ammonia, and/or copperethylenediamine. The copper-amine complex is usually in an aqueoussolution. Preferred precipitates comprise copper hydroxides. Theparticles may be prepared by modifying a pH of the mixture comprisingcopper and the amine. For example, the pH of a mixture comprising copperand an amine may be reduced to value sufficient to precipitatecopper-based particles. In any event, the mixture comprising copper andthe amine may be diluted with water to have a copper concentration of atleast about 0.25, for example, at least about 0.5, such as at leastabout 1% by weight. The copper concentration may be less than about 2%,for example, less than about 1.5%. The pH of the mixture comprisingcopper and the amine, such as the diluted mixture, may be reduced usingacid to prepare a precipitate comprising copper-based particles. Theparticles may comprise copper hydroxide. A dispersant may be added tothe mixture, such as before obtaining the precipitate, upon obtainingthe precipitate, or thereafter. A stable aqueous copper-amine complexsolution may have a pH of 8 to 13. One method for preparing theprecipitate comprises adjusting the pH of an aqueous mixture of thecopper-amine complexes. In one embodiment, the pH is adjusted so thatthe pH is at least about 4, for example, at least about 5.5. The pH ofthe mixture may be adjusted to less than about 8, for example, to lessthan about 7.5, such as less than about 7. The pH may be adjusted toabout 7. The pH is adjusted by adding an acid to the mixture.Alternatively, the pH may be adjusted by adding the mixture to acid. Thesolution of copper-amine complex may be prepared in the presence ofacid. Suitable acids for adjusting the pH include, for example, sulfuricacid, nitric acid, hydrochloric acid, formic acid, boric acid, aceticacid, carbonic acid, sulfamic acid, phosphoric acid, phosphorous acid,and/or propionic acid. The anion of the acid used may be partiallyincorporated in the precipitated salt.

One embodiment of a method for preparing copper-based particlescomprises precipitation of copper-based particles from a solutioncomprising (a) copper, such as in the form of a copper salt, and (b) apH modifying agent, such as a hydroxide. Exemplary hydroxides may beselected from hydroxides of group 1a and/or group 2a elements, such assodium and potassium hydroxide.

Copper salts useful in preparing copper-based particles of the inventionpreferably comprise water soluble salts of copper and another material.An exemplary copper salt may include at least one of a copper sulfate, ahalogen-containing copper salt, such as copper chloride or copperbromide, a copper nitrate, a copper acetate, a copper formate, and acopper propionate. The one or more copper salts may be provided in theform of a solution, such as an aqueous solution, of a liquid and thecopper salt.

U.S. Pat. No. 4,808,406, the disclosure of which is incorporated byreference, describes a useful method for producing finely divided stablecupric hydroxide compositions of low bulk density comprising contactingsolutions of an alkali metal carbonate or bicarbonate and a copper salt,precipitating a basic copper carbonate-basic copper sulfate to a minimumpH in the range of greater than 5 to about 6, contacting the precipitatewith an alkali metal hydroxide and converting basic copper sulfate tocupric hydroxide. Another method of manufacturing the copper compoundsis the method described in U.S. Pat. No. 4,404,169, the disclosure ofwhich is incorporated by reference. This patent describes a process ofproducing cupric hydroxides having stability in storage if phosphateions are added to a suspension of copper oxychloride in an aqueousphase. The copper oxychloride is then reacted with alkali metalhydroxide or alkaline earth metal hydroxide, and the cupric hydroxideprecipitated as a result of the suspension is washed and thenre-suspended and subsequently stabilized by the addition of acidphosphate to adjust a pH value of 7.5 to 9. The suspended copperoxychloride is preferably reacted in the presence of phosphate ions inan amount of 1 to 4 grams per liter of the suspension and at atemperature of 20° to 25° C. and the resulting cupric hydroxide isstabilized with phosphate ions.

There are numerous methods of preparing very small particles of coppersalts, and the above list is exemplary and not complete. The simplestand by far the least expensive method of producing small particles is astandard precipitation of admixing two solutions, one containing solublecopper and one containing the desired anion, and some particlesresulting from slightly modified precipitation processes are of a sizethat may be injected into the wood. The most useful modification issimply adding small quantities of anion to a concentrated solution ofthe cation, or vice versa, with vigorous stirring. Examples in the priorart show an average particle size as low as 0.3 microns was obtainable.Such processes are also desirable because the cost of counter-ions(those ions that form the salts that are admixed, but that are notincorporated into the substantially crystalline (or amorphous sparinglysoluble) copper material) is negligible. Standard materials such aschlorides, sulfates, ammonia, and the like are common counterions.Further, the material need not be ultra-pure. Indeed, it is desirable tohave one or more “contaminants” in the precipitating solutions. Smallerdiameters are obtained when the concentration of impurities such as Mg,Ca, Zn, Na, Al and Fe in the suspension is high. Fe present in thesuspension acts especially strongly to prevent formation oflarge-diameter cuprous hydroxide particles. Fe concentration ispreferably greater than 70 ppm to obtain smaller particles.

In one embodiment, copper and a hydroxide are combined to prepare aprecipitate comprising copper. The copper and hydroxide may be combinedwith the copper in the form of a copper salt. For example, a solutioncomprising at least one copper salt and a solution comprising at leastone hydroxide may be combined to precipitate copper-based particles. Inone embodiment, the method includes precipitating copper-based particlesfrom a solution comprising at least one other metal, such as a salt ofat least one other metal. For example, copper-based particles of theinvention may be precipitated from a solution comprising at least one ofone or more group 2a metals such as magnesium or salts thereof. Themetal or salt of the metal may be zinc. In one embodiment, (a) asolution comprising a copper salt and at least one other metal, whichmay be in the form of one or more salts, and (b) a solution comprising ahydroxide are combined in amounts sufficient to precipitate copper-basedparticles, such as particles comprising copper hydroxide.

In one embodiment, particles are prepared by adding a copper saltsolution to a hydroxide solution comprising about 20% hydroxide byweight. The copper salt solution is added until a desired amount ofcopper-based particles are obtained. For example, the copper saltsolution may be added until the pH of the hydroxide solution falls to atleast about 11.5, 11, 10.5, or about 10. The precipitate comprising theprecipitated copper-based particles may be used directly to protect woodor wood products, but are beneficially milled to reduce the fraction ofparticulates having a diameter above 1 micron.

Copper hydroxide is not particularly stable. Hydroxides can be changedto oxides by for example, a quick and exothermic reaction by exposure ofthe copper hydroxide particles to aqueous solution of glucose. Copperhydroxide may react with air, sugars, or other compounds to partially orcompletely form copper oxide. While this is generally of less concernwith foliar fungicides, the conditions for conversion are highly favoredduring kiln-drying treated wood, which contains gluconuronic acids,which are sugar-like molecules, and heat and a dehydrating condition,create a high probability of such transformation occurring within thewood.

However, as taught by U.S. Pat. No. 3,231,464, the disclosure of whichis incorporated herein by reference thereto, the presence of magnesiumor magnesium and zinc can help stabilize cupric hydroxide fromconverting to copper oxide via the loss of a water molecule. Thepreferred copper hydroxide particles used in this invention arestabilized. U.S. Pat. No. 3,231,464 teaches stabilizing the copperhydroxide with added magnesium zinc, or both, at a Cu:Mg and/or Cu:Znweight ratio of 8:1. Copper hydroxide prepared in a manner so as tocontain significant magnesium and/or zinc hydroxides are more stable andresistant to degradation to copper oxides. The preferred copperhydroxide particle's comprise between 50% and 90% copper hydroxide, withthe remainder comprising zinc hydroxide, magnesium hydroxide, or both.The process described in U.S. Pat. No. 3,231,464 is inexpensive, andwith modifications produces particulates with a particle sizedistribution with a median particle size of a few tenths of a micron.

While such methods can provide small particles of selected substantiallycrystalline (or amorphous sparingly soluble) salts, these processesusually have a small fraction of particles that are unacceptably large.Generally, however, a few particles from a normal precipitation processare too big to be injectable. A very small fraction of particles havinga particle size above about 1 micron causes, in injection tests on woodspecimens, severely impaired injectability. Large particles, e.g.,greater than about 1 micron in diameter, should be removed. Removal viafiltering is not effective, as a large fraction of injectable particleswill be caught on filters designed to remove the bigger particles. Wehave surprisingly found that milling, for example wet-milling, canadvantageously modify particle size and morphology. Particles can besmoothed and large particles removed by continuous-process centrifuging.Alternately, as described above, we have surprisingly found thatsubstantially crystalline (or amorphous sparingly soluble) copper-basedparticulates that are manufactured by a precipitation process, usingconditions known in the art to produce small particles, can be readilymilled into an injectable material by wet milling with a millingmaterial such as 0.5 mm diameter zirconium silicate in a matter ofminutes.

In another embodiment, the copper-based particulates can have asubstantial amount, e.g., at least 0.5% by weight, for example at least2% by weight, but less than 50% by weight based on the weight of copperof one or more other cations, either dispersed within the substantiallycrystalline (or amorphous sparingly soluble) copper composition orsubstantially as a separate phase within the particulate. In a preferredembodiment, the copper-based particulates can have a substantial amountof one or more of magnesium, zinc, or both, wherein these cations areeither dispersed within the substantially crystalline (or amorphoussparingly soluble) copper composition or be a separate phase within aparticulate. The weight ratio of copper to zinc may range between99.9:0.1 to 1:1, but is preferably between 99.5:0.5 to 90:10, forexample between 99:1 and 94:6. The weight ratio of copper to magnesiummay range between 99.9:0.1 to 1:1, but is preferably between 99.5:0.5 to85:15, for example between 95:5 and 90:10.

In one embodiment of the invention, copper-based particles areprecipitated from a mixture of a copper salt solution and a hydroxide(and optionally other anions) in the presence of at least one group 2ametal or salt thereof, such as magnesium or a magnesium salt. In oneembodiment, the copper-based particles are precipitated from a mixturecomprising at least about 0.05 parts magnesium, for example at leastabout 0.1 parts magnesium per 9 parts copper. The mixture may compriseat least about 0.25 parts magnesium per 9 parts copper. The mixture maycomprise less than about 1.5 parts magnesium, for example, less thanabout 1.0 parts, or less than about 0.75 parts magnesium per 9 partscopper.

Copper-based particles prepared in accordance with the present inventionwill comprise a group 2a metal or zinc if such materials (metal ions)were used in preparation of the particles. In another embodiment, thecopper-based particles are precipitated from a mixture comprising atleast about 0.2 parts magnesium, for example, at least about 0.25 partsmagnesium per 22.5 parts copper. The mixture may comprise at least about0.5 parts magnesium per 22.5 parts copper. The mixture may comprise lessthan about 3.5 parts magnesium, for example, less than about 2.5 partsmagnesium, or less than about 2 parts magnesium per 22.5 parts copper.The parts here merely reflect weight ratios of the cations in thesolution to be precipitated, and the parts do not imply concentration.

Alternatively, or in combination with the group 2a metal or saltthereof, the copper-based particles may be precipitated from a solutioncomprising zinc metal or salt thereof. For example, the mixture maycomprise at least about 0.1 parts zinc, for example, at least about 0.25parts zinc, at least about 1.0 parts zinc, or at least about 2.0 partszinc per 22.5 parts copper. The mixture may comprise less than about 3.0parts zinc, for example, less than about 2.5 parts zinc, or less thanabout 1.5 parts zinc per 22.5 parts copper. Preferably, the mixtureadditionally comprises at least about 0.25 parts magnesium, for example,at least about 0.5 parts magnesium, at least about 1.0 parts magnesium,or at least about 2 parts magnesium per 22.5 parts copper. The mixturemay comprise less than about 5.0 parts magnesium, for example, less thanabout 2.5 parts magnesium, or less than about 2 parts magnesium per 22.5parts copper. Table I sets forth exemplary ratios of zinc, magnesium,and copper in accordance with the present invention.

TABLE I Exemplary Formulations To Precipitate Mg/Zn-Stabilized CopperHydroxide Formulation Parts Zinc Parts Magnesium Parts Copper 1 0.5 0.522.5 2 0.75 0.75 22.5 3 1.5 1.5 22.5 4 2.5 1.0 22.5 5 2.5 2.5 22.5

Such mixtures can be used to precipitate copper hydroxides, basic coppercarbonate, copper oxychloride, copper borate, and any of thesubstantially crystalline (or amorphous sparingly soluble) saltsdescribed herein.

In alternative embodiments, the particulates can comprise particles thatcontain a substantially crystalline (or amorphous sparingly soluble)copper composition with between 0.001% and 3%, preferably 0.005% to0.5%, for example 0.01% to 0.1% by weight of silver, based on the weightof copper, and also optionally the other cations. Silver is expensivebut is efficacious against some bio-organisms in very small amounts, andtherefore silver is a useful co-cation in a substantially crystalline(or amorphous sparingly soluble) copper-based particulate. A woodtreatment containing 0.25 pounds copper per cubic foot would comprise,at a 0.04% silver loading relative to copper, less than 0.2 ounces ofsilver per one hundred cubic feet of wood. Generally, if silver isincorporated into the substantially crystalline (or amorphous sparinglysoluble) copper phase, the substantially crystalline (or amorphoussparingly soluble) copper phase is preferably a copper(I) salt and thesilver ions are disposed homogenously through the substantiallycrystalline (or amorphous sparingly soluble) copper phase, to preventthe minute quantities of silver from being prematurely leached from thewood.

Yet another embodiment of the invention is an effective, long-lasting,environmentally responsible, non-staining/coloring, inexpensive,non-corrosion-inducing, injectable, substantially crystalline (oramorphous sparingly soluble), zinc-based particulate preservativetreatment for wood and wood products that is substantially free ofhazardous material. This composition can be used independently of thecopper-based particulates, but in preferred embodiments is used incombination with one or more copper-based particulates. Modification ofthe above processes to produce substantially crystalline (or amorphoussparingly soluble) zinc-containing particulates is within the ability ofone of ordinary skill in the art, and such modifications will not bedescribed here.

Similarly, modifications of the above processes to produce substantiallycrystalline (or amorphous sparingly soluble) zinc-containingparticulates are within the ability of one of ordinary skill in the art,and such modifications will not be described here.

Milling—Generally, the simple, inexpensive copper salt precipitationprocesses provide particles with a size too great for injection. Evenfor processes that provide very small median diameter particles, suchas, a few tenths of a micron in diameter, the precipitation processseems to result in a small fraction of particles that are larger thanabout 1 micron, and these particles plug up pores and prevent acceptableinjectability. The size distribution of the injectable particles musthave the vast majority of particles, for example at least 95% by weight,preferably at least 99% by weight, more preferably at least 99.5% byweight, be of an average diameter less than about 1 micron, andadvantageously the particles are not rod-shaped with a single longdimension. Average particle diameter is beneficially determined byStokes Law to a size down to about 0.2 microns. Smaller sizes arebeneficially determined by, for example, a dynamic light scatteringmethod or laser scattering method or electron microscopy. Generally,such a particle size and particle size distribution can be achieved bymechanical attrition of particles.

Attrition can be obtained for example 1) by use of a pressurehomogenizer such as that manufactured by SMT Ltd. having 400 kg/cm² ofpressure at a flow rate of 1 l/min., though such a system often requiresthe slurry be processed overnight; by processing in an ultrasonichomogenizer such as is manufactured by Nissei Ltd., though such a methodis energy intensive; by wet milling in a sand grinder charged with forexample partially stabilized zirconia beads with diameter 0.5 mm;alternately wet milling in a rotary sand grinder with partiallystabilized zirconia beads with diameter 0.5 mm and with stirring at forexample 1000 rpm; or by use of a wet-ball mill, an attritor (e.g.,manufactured by Mitsui Mining Ltd.), a perl mill (e.g., manufactured byAshizawa Ltd.,), or the like. Attrition can be achieved to a lesserdegree by centrifugation, but larger particles can be simply removedfrom the composition via centrifugation. Removing the largerparticulates from a composition can provide an injectable formulation.Said particulates can be removed by centrifugation, where settlingvelocity substantially follows Stokes law. While this process providesinjectable slurries, a fraction of the copper-containing particulatesthat are separated thereby include both large particles as well as aportion of the injectable particles, and generally this material wouldbe recycled by being dissolved and precipitated. Such a process adds anadditional cost to forming the injectable copper-containing particulatewood treatment.

The most effective method of modifying the particle size distribution iswet milling. Beneficially all injectable formulations for wood treatmentshould be wet-milled, even when the “mean particle size” is well withinthe range considered to be “injectable” into wood. Traditionalprecipitation techniques are known to produce particles with a medianparticle size between about 0.2 and 6 microns, depending on the saltsused as well as on various reaction conditions. For example, acommercially available copper-based particulate product, a magnesiumstabilized form of copper hydroxide (available from Phibro-Tech., Inc.)has a mean particle size of about 200 nm. However, when this materialwas slurried and injected into wood, there was unacceptable plugging onthe face of the wood. Careful examination found the precipitationprocess used by Phibro-Tech., Inc. resulted in a few weight percent ofparticles with a size over 1 micron, and this small amount of materialwas hypothesized to form the start of the plug (where smaller, normallyinjectable particles were subsequently caught by the plug). Wet millingwith 2 mm zirconium silicate media had no effect—wet milling for daysresulted in only a marginal decrease in particle size, and the materialwas still not injectable in commercial quantities.

However, we surprisingly found that a milling process using 0.5 mm highdensity zirconium silicate grinding media provides further efficientattrition, especially for the removal of particles greater than about 1micron in the commercially available copper-based particulate productavailable from Phibro-Tech., Inc. The milling process usually takes onthe order of minutes to achieve almost complete removal of particlesgreater than 1 micron in size. This wet milling process is inexpensive,and all of the precipitate can be used in the injectable coppercontaining particulate wood treatment. The selection of the millingagents is not critical, and can be zirconia, partially stabilizedzirconia, zirconium silicate, and yttrium/zirconium oxide, for example,recognizing that the more dense materials give faster particle sizeattrition. The size of the milling material is believed to be important,even critical, to obtaining a commercially acceptable process. Themilling agent material having a diameter of 2 mm or greater areineffective, while milling agent material having a diameter of 0.5 mm iseffective typically after 15 minutes of milling. We believe the millingagent is advantageously of a diameter less than 1.5 mm, preferably isless than 1 mm in diameter, for example between about 0.1 mm and about 1mm, or alternately between about 0.3 mm and 0.7 mm.

The original focus on injectability focused on the magnesium stabilizedcopper hydroxide product available from Phibro-Tech., Inc., as thismaterial started (and ended) with a material that had a median diameterof 0.2 microns. While we originally believed that the milling brokeaggregates, possibly fused aggregates, of smaller particles that formedthe “greater than about 1 micron fraction” of the above-describedproduct, the milling process was surprisingly equally effective onlarger mean diameter particles.

We have surprisingly found that copper-based particulates that aremanufactured by a straightforward precipitation process, usingconditions known in the art to produce small particles, e.g., particleshaving a size less than 10 microns, can be readily milled into aninjectable material. Therefore, milling other precipitate material with0.5 mm diameter zirconium silicate (or any comparable product, e.g., a0.1 mm to 1 mm sized zirconium silicate or zirconium oxide) can mill ina matter of minutes a substantially crystalline (or amorphous sparinglysoluble) powder material having a larger initial average size into aproduct that can be readily injected into wood. Milling with 0.5 mmzirconium silicate media not only quickly reduced further the magnesiumstabilized copper hydroxide product, but this grinding medium was alsofound to be effective on other forms of basic copper compounds such asother stabilized copper hydroxides, copper carbonate, tribasic coppersulfate, copper oxychloride, and copper oxides. The results of millingof a variety of materials with the 0.5 mm milling material describedabove for 15 minutes are shown in Table 2. Copper hydroxide materialwith an initial median size of 2.5 microns was quickly milled to aninjectable material having a median particle size of 0.3 microns.Additional milling time would doubtless further reduce the median andaverage particle size. A copper carbonate material having a median sizeof 3.4 microns was milled to a material having a median size of lessthan 0.2 microns. FIG. 1 shows the face of wood injected with unmilledproduct and the face of wood injected with the milled product. In thecolor photographs the plugging is especially visible. A tribasic coppersulfate material having a median size of 6.2 microns was milled to amaterial having a median size of less than 0.2 microns. A copperoxychloride material having a median size of 3.3 microns was milled to amaterial having a median size of 0.4 microns.

TABLE 2 Average Particle size (from Stokes Law Settling) Before andAfter Milling With 0.5 mm Zirconium Silicate Median Particle SizeDistribution Data PS % < 10 % < 1 % < 0.4 % < 0.2 Description (microns)um um um um Ref: Copper Hydroxide, After <0.2 99.0 96.7 94.6 84.9V.216.69 Dettwiler Treat Copper Hydroxide, Before <0.2 99.7 84.0 63.957.1 V.216.69 Dettwiler Copper Hydroxide, After 0.30 99.7 95.4 21.7 —V.216.74 Furness Treat Copper Hydroxide, Before 2.5 99.6 8.7 — —V.216.74 Furness Copper Carbonate After <0.2 99.1 97.2 96.9 87.3V.216.77 Treat Copper Carbonate Before 3.4 98.0 1.2 — — V.216.77Tribasic Copper After <0.2 99.5 96.4 90.5 55.1 V.216.85 Sulfate TreatTribasic Copper Before 6.2 69.5 16.5 — — V.216.85 Sulfate Copper After0.38 99.4 93.9 63.2 — V.218.7 Oxychloride Treat Copper Before 3.3 98.52.8 — — V.218.7 Oxychloride

Milling is believed to break up larger particles. It would also breakparticles having one large dimension, e.g., rod-like particles, whichare know to have injection problems. Milling can be combined with, forexample, centrifugation to create a more uniform product. Alternatively,milling can be combined with a coating process to form a more stablematerial.

Specific substantially crystalline (or amorphous sparingly soluble)copper-containing materials and other copper-containing materials usefulin embodiments of this invention will be described below. In eachinstance, the zinc analog is useful for zinc-based particulates.Generally, the tin analogs can also be useful for tin-basedparticulates.

Copper Oxides—In one embodiment, the substantially crystalline coppercomposition in a plurality of copper-based particulates can comprise oneor more copper oxides. Of the copper oxides, Cu₂O is preferred over CuO,as the Cu₂O is subject to oxidation by oxygen dissolved in water whichappears to increase the kinetics of dissolution. If the copper-basedparticulate material consists essentially of one or more copper oxides,however, the material will not be sufficiently bioactive. In onevariant, the copper oxide material can have a substantial amount of oneor more of magnesium, zinc, or both, wherein these cations are eitherdispersed within the substantially crystalline (or amorphous sparinglysoluble) copper composition or be a separate phase within a particulate.Generally, magnesium and zinc co-cations can help stabilize copperhydroxide and prevent its natural transition to copper oxide. We believeif substantial amounts of zinc and especially magnesium are included inthe crystalline copper oxide material, it will partially disrupt thecrystal and therefore encourage solubility. Copper oxides are lesspreferred than other substantially crystalline (or amorphous sparinglysoluble) copper compounds, because the rate of dissolution is so slow.If the crystalline copper in the particles is more than 60% copperoxide, then preferably the particles have a maximum size of about 50nanometers, or have a BET surface area of at least 300 m2/gm, or both.The particulates may need special treatments and/or properties toprovide a bio-active copper concentration, and are more easily flushedfrom the wood.

In any of the below-described embodiments, the substantially crystalline(or amorphous sparingly soluble) copper composition in copper-basedparticulates and/or copper-based particulate material can furthercomprise one or more copper oxides. Of the copper oxides, CuO ispreferred over Cu₂O.

Copper hydroxides—In a preferred embodiment the substantiallycrystalline (or amorphous sparingly soluble) copper composition in aplurality of copper-based particulates can comprise or consistessentially of copper hydroxides. In a variant of this, the copper-basedparticulate material can comprise or consist essentially of copperhydroxides. Of the copper hydroxides, copper hydroxide including CuOH(usually not stable) and/or Cu(OH)₂ can be used, though Cu(OH)₂ ispreferred over CuOH. In a preferred embodiment of any of the above, thesubstantially crystalline (or amorphous sparingly soluble) coppercomposition can have a substantial amount of one or more of magnesium,zinc, or both, wherein these cations are either dispersed within thesubstantially crystalline (or amorphous sparingly soluble) coppercomposition or be a separate phase within a particulate.

Basic Copper Carbonate—In another preferred embodiment the substantiallycrystalline copper composition in a plurality of copper-basedparticulates can comprise or consist essentially of alkaline (or“basic”) copper carbonates. While various compositions comprising copperhydroxide and copper carbonate are envisioned, typically alkaline coppercarbonate is [CuCO₃×Cu(OH)₂]. In a variant of this, the copper-basedparticulate material can comprise or consist essentially of alkalinecopper carbonate. In a preferred embodiment of any of the above, thesubstantially crystalline (or amorphous sparingly soluble) coppercomposition can have a substantial amount of one or more of magnesium,zinc, or both, wherein these cations are either dispersed within thesubstantially crystalline (or amorphous sparingly soluble) coppercomposition or be a separate phase within a particulate.

Copper Carbonate—In another embodiment the substantially crystallinecopper composition in a plurality of copper-based particulates cancomprise or consist essentially of copper carbonate, e.g., CuCO₃. In avariant of this, the copper-based particulate material can comprise orconsist essentially of alkaline copper carbonate. In a preferredembodiment of any of the above, the substantially crystalline (oramorphous sparingly soluble) copper composition can have a substantialamount of one or more of magnesium, zinc, or both, wherein these cationsare either dispersed within the substantially crystalline (or amorphoussparingly soluble) copper composition or be a separate phase within aparticulate. Copper carbonate is less preferred than basic coppercarbonate, as the OH groups in the latter help keep the pH elevated,thereby reducing copper mobility.

Tribasic Copper Sulfates—In another preferred embodiment thesubstantially crystalline copper composition in a plurality ofcopper-based particulates can comprise or consist essentially of basiccopper sulfates. In a variant of this, the copper-based particulatematerial can comprise or consist essentially of basic copper sulfates.While various compositions comprising copper hydroxide and coppersulfate are envisioned, typically alkaline copper sulfate is[CuSO₄×3Cu(OH)₂]. If tribasic copper sulfate is used, the substantiallycrystalline (or amorphous sparingly soluble) copper composition canadditionally advantageously have a substantial amount of one or more ofmagnesium, zinc, or both, wherein these cations are either dispersedwithin the substantially crystalline (or amorphous sparingly soluble)copper composition or be a separate phase within a particulate.

Alkaline Copper Nitrates—In another embodiment the substantiallycrystalline copper composition in a plurality of copper-basedparticulates can comprise or consist essentially of alkaline coppernitrates. In a variant of this, the copper-based particulate materialcan comprise or consist essentially of alkaline copper nitrates. Whilevarious compositions comprising copper hydroxide and copper nitrate areenvisioned, typically alkaline copper nitrate is [Cu(NO₃)×3Cu(OH)₂]. Ifalkaline copper nitrate is used, the substantially crystalline (oramorphous sparingly soluble) copper composition can additionallyadvantageously have a substantial amount of one or more of magnesium,zinc, or both, wherein these cations are either dispersed within thesubstantially crystalline (or amorphous sparingly soluble) coppercomposition or be a separate phase within a particulate. In the mostpreferred embodiments of this invention, the wood preservative issubstantially free of copper nitrates, as the nitrogen, may during thedegradation process, eventually act as foodstuff for one or morebio-organisms.

Copper Oxychlorides—In another preferred embodiment the substantiallycrystalline copper composition in a plurality of copper-basedparticulates can comprise or consist essentially of copper oxychlorides.In a variant of this, the copper-based particulate material can compriseor consist essentially of copper oxychlorides. While variouscompositions comprising copper hydroxide and copper chloride areenvisioned, typically copper oxychloride is [CuCl₂×3Cu(OH₃]. In apreferred embodiment of any of the above, the substantially crystalline(or amorphous sparingly soluble) copper composition can have asubstantial amount of one or more of magnesium, zinc, or both, whereinthese cations are either dispersed within the substantially crystalline(or amorphous sparingly soluble) copper composition or be a separatephase within a particulate.

Copper Borate—In another preferred embodiment the substantiallycrystalline copper composition in a plurality of copper-basedparticulates can comprise or consist essentially of copper borate.Copper borate includes basic copper borate. In a variant of this,substantially crystalline (or amorphous sparingly soluble) coppercomposition can have a substantial amount of one or more of magnesium,zinc, or both, wherein these cations are either dispersed within thesubstantially crystalline (or amorphous sparingly soluble) coppercomposition or be a separate phase within a particulate. Generally, thecopper borate is advantageously included in a composition that alsocomprises copper hydroxide or one or more of the basic copper anionsalts, to help moderate pH and reduce solubility of the copper borate.

Copper ferricyanate—In any of the above-described embodiments, thesubstantially crystalline (or amorphous sparingly soluble) coppercomposition in copper-based particulates and/or copper-based particulatematerial can further comprise copper ferricyanate. This embodimentincludes less preferably copper ferricyanide. Alternatively, thesubstantially crystalline (or amorphous sparingly soluble) coppercomposition in the copper-based particulates can comprise or consistessentially of copper ferricyanate, Cu₂[Fe(CN)₆]. In another embodiment,the copper-based particulate material can comprise or consistessentially of copper ferricyanate.

Copper Fluorosilicate—The substantially crystalline (or amorphoussparingly soluble) copper composition in copper-based particulatesand/or copper-based particulate material can comprise copperfluorosilicate. Alternatively, the substantially crystalline (oramorphous sparingly soluble) copper composition in the copper-basedparticulates can comprise or consist essentially of copperfluorosilicate. In another embodiment, the copper-based particulatematerial can comprise or consist essentially of copper fluorosilicate.

Copper Thiocyanate—In any of the above-described embodiments, thesubstantially crystalline copper composition in copper-basedparticulates and/or copper-based particulate material can furthercomprise copper thiocyanate, though it is generally difficult tomanufacture crystalline copper thiocyanate. Alternatively, the coppercomposition in the copper-based particulates can comprise or consistessentially of CuSCN. In another embodiment, the copper basedparticulate material can comprise or consist essentially of CuSCN.

Copper diphosphate or Copper pyrophosphate—In any of the above-describedembodiments, the substantially crystalline copper composition incopper-based particulates and/or copper-based particulate material canfurther comprise copper pyrophosphate, Cu₂P₂O₇. Alternatively, thesubstantially crystalline (or amorphous sparingly soluble) coppercomposite on in the copper-based particulates can comprise or consistessentially of copper pyrophosphate. In another embodiment, thecopper-based particulate material can comprise or consist essentially ofcopper pyrophosphate.

Copper Cyanate and/or Copper Cyanate—Copper cyanide, Cu(CN)₂, and coppercyanate, Cu(CNO), are each a sparingly soluble copper salt, but they aretoo dangerous to be useful for copper-based wood preservativetreatments. When even a small quantity of copper cyanate and/or coppercyanide is used, the formulation must be basic, that is, contained in analkaline formulation.

The copper-based particulates can comprise or consist essentially of anyof the above listed sparingly soluble copper compounds. In anotherpreferred embodiment the substantially crystalline (or amorphoussparingly soluble) copper composition in the copper-based particulatesin a wood preservative formulation can comprise or consist essentiallyof a plurality of sparingly soluble substantially crystalline (oramorphous sparingly soluble) copper salts selected from copper oxide,copper hydroxides; copper carbonates, alkaline (or “basic”) coppercarbonates; alkaline copper sulfates; alkaline copper nitrates; copperoxychlorides; copper borates, and mixtures thereof, with the provisothat at least one of the substantially crystalline (or amorphoussparingly soluble) copper salts is not a copper oxide. In a variant ofthis, the copper-based particulate material can comprise or consistessentially of one or more sparingly soluble substantially crystallinecopper salts selected from copper hydroxides; copper carbonates,alkaline (or “basic”) copper carbonates; alkaline copper nitrates;alkaline copper sulfates; copper oxychlorides; copper borates, andmixtures thereof. In any of the above, the substantially crystalline (oramorphous sparingly soluble) copper composition can have a substantialamount of one or more of magnesium, zinc, or both, wherein these cationsare either dispersed within the substantially crystalline (or amorphoussparingly soluble) copper composition or be a separate phase within aparticulate.

In preferred embodiments of the invention, at least some particulatescomprise copper hydroxide, basic copper carbonate, or both. In morepreferred embodiments, the copper hydroxide comprises between 6 and 20parts of magnesium per 100 parts of copper, for example between 9 and 15parts of magnesium per 100 parts of copper. Alternatively, in anothermore preferred embodiments, the copper hydroxide comprises between 6 and20 parts total of magnesium and zinc per 100 parts of copper, forexample between 9 and 15 parts total of magnesium and zinc per 100 partsof copper. In some embodiments, the basic copper carbonate comprisesbetween 6 and 20 parts of magnesium per 100 parts of copper, for examplebetween 9 and 15 parts of magnesium per 100 parts of copper, oralternatively between 6 and 20 parts total of magnesium and zinc per 100parts of copper, for example between 9 and 15 parts total of magnesiumand zinc per 100 parts of copper. Alternatively or additionally, in apreferred embodiment, the copper hydroxide and/or basic copper carbonatecomprises between about 0.01 and about 5 parts of phosphate per 100parts of copper, for example between 9 and 15 parts of phosphate per 100parts of copper.

In another preferred embodiment, slurry comprises a sparingly solublecopper salt particulates and also comprises zinc borate particulates.Preferably at least some of the sparingly soluble copper salt-basedparticulates comprise copper borate. It is known to use a two stageprocess where a zinc or copper salt is injected into the wood followedby a second step wherein the borax is injected and the insoluble metalborate is formed in situ. Such a complicated, time consuming, andtherefore expensive process is not sufficiently cost-effective. As thesolubility of copper borate is very pH sensitive, in a preferredembodiment the sparingly soluble copper salts comprise an alkalinematerial, e.g., copper hydroxide or copper carbonate, to reduce thesolubility of the copper borate.

Soluble Substantially Crystalline Copper Salts—In any of theabove-described embodiments, the substantially crystalline coppercomposition in copper-based particulates and/or copper-based particulatematerial can further comprise one or more soluble substantiallycrystalline copper salts, for example copper sulfate, copperfluoroborate; copper fluoride, or mixtures thereof, where the solublesubstantially crystalline copper salts phase is stabilized againstdissolution. Alternatively, the substantially crystalline coppercomposition in the copper based particulates can comprise or consistessentially of one or more soluble substantially crystalline coppersalts, for example, copper fluoroborate; copper sulfate, copperfluoride, or mixtures thereof, where the soluble substantiallycrystalline copper salts phase is stabilized against dissolution. Suchprotection may be provided by encasing the soluble copper salts in ashell or a matrix of sparingly soluble copper salts or in insolublecopper salts, such as copper phosphate.

In another embodiment, the copper-based particles may be essentiallyfree of halogen, which means that the weight percent of halogen in theparticles is less than about 2.5%. Preferably, the weight percent ofhalogen in copper-based particles that are essentially free of halogenis less than about 1%. The copper-based particles may be free ofhalogen.

Copper Phosphate—In any of the above-described embodiments, thesubstantially crystalline copper composition in copper-basedparticulates and/or copper-based particulate material can furthercomprise the substantially insoluble copper salt copper phosphate,Co₃(PO₄)₂. Alternatively, the substantially crystalline (or amorphoussparingly soluble) copper composition in the copper-based particulatescan comprise or consist essentially of Cu₃(PO₄)₂. Generally, inpreferred embodiments, if Cu₃(PO₄)₂ is present it is a coating overother sparingly soluble copper salts, wherein the Cu₃(PO₄)₂ provides afairly inert coating for a period of time before it dissolves orpartially dissolves. If there are copper-based-particulatessubstantially comprising Cu₃(PO₄)₂ and/or copper oxide, the particulatesshould be exceedingly small, e.g., less than about 0.05 microns,preferably less than about 0.04 microns, to provide maximum surface areato help dissolution of the particles, and the wood treatment shouldcontain another type of substantially crystalline (or amorphoussparingly soluble) copper-based particulates, e.g., basic coppercarbonate, copper borate, tribasic copper sulfate, copper hydroxides,and the like.

Copper 8-Quinolinolate—In any of the above-described embodiments, thecopper composition in copper-based particulates and/or copper-basedparticulate material can further comprise the insoluble copper saltcopper 8-quinolinolate. Alternatively, the copper composition in thecopper-based particulates can comprise or consist essentially of copper8-quinolinolate. Generally, in preferred embodiments, if copper8-quinolinolate is present it is a coating over other sparingly solublecopper salts, wherein the copper 8-quinolinolate provides a fairly inertcoating for a period of time before it dissolves or partially dissolves.If there are copper-based particulates substantially comprising copper8-quinolinolate, the particulates should be exceedingly small, e.g.,less than about 0.01 microns, preferably less than about 0.005 microns,to provide maximum surface area to help dissolution of the particles.

In any of the above-described embodiments, the composition can furthercomprise copper quinaldate, copper oxime, or both in particulate form.

In one embodiment, the copper-based particles comprise a substantiallycrystalline copper compound. At least about 20%, 30%, 50%, or 75% of theweight of the copper-based particles may be composed of thesubstantially crystalline copper compound. In another embodiment,essentially all (e.g., more than 90%, for example more than 95%) of theweight of the copper-based particles is composed of substantiallycrystalline copper compound. In preferred embodiments the particlecomprises at least about 20%, preferably at least about 30%, and morepreferably at least about 50%, for example at least about 75% by weightof one or more sparingly soluble copper salts. In another embodiment,essentially all (e.g., more than 90%, for example more than 95%) of theweight of the copper-based particles is composed of substantiallycrystalline copper compound(s).

In one embodiment of the invention, the copper-based particles aresubstantially free of at least one of the halogens, for example, atleast one of fluorine, chlorine, bromine, and iodine. Preferably, theweight percent of the at least one halogen in particles that aresubstantially free of the at least one halogen is less than about 25%,for example, less than about 20%, 15%, 10%, or 5%.

In one embodiment, the copper-based particles are essentially free of atleast one of the halogens, for example at least one of fluorine,chlorine, bromine, and iodine. Particles that are essentially free of atleast one halogen have less than about 2.5% of the at least one halogen.Preferred particles have less than about 1% of the at least one halogen.In one embodiment, the copper based particles are free of at least oneof the halogens.

In another embodiment, the copper-based particles may be substantiallyfree of halogen. Preferably, the weight percent of halogen incopper-based particles that are substantially free of halogen is lessthan about 25%, for example, less than about 20%, 15%, 10%, or 5%.

Again, the zinc analogs of the above are useful for the zinc-basedparticulates of the alternate embodiments of the invention. In oneembodiment the copper-based particulate material can further compriseone or more of crystalline zinc salts selected from zinc hydroxide; zincoxides; zinc carbonate; zinc oxychloride; zinc fluoroborate; zincborate, zinc fluoride, or mixtures thereof. The zinc salts may be in aseparate salt phase, or may be mixed CU/Zn salts, or combinationsthereof. In preferred embodiments the particle comprises at least about40%, preferably at least about 60%, and more preferably at least about80% by weight of one or more substantially crystalline (or amorphoussparingly soluble) copper salts, crystalline zinc salts, or mixtures orcombinations thereof.

In one embodiment the copper-based particulate preservative treatmentfor wood can further comprise zinc-based particulates comprising one ormore of crystalline zinc salts selected from zinc hydroxide; zincoxides; zinc carbonate; zinc oxychloride; zinc fluoroborate; zincborate, zinc fluoride, or mixtures thereof. The preferred zinc-basedsubstantially crystalline material are zinc hydroxide, zinc borate, zinccarbonate, or mixture thereof, which may be doped with other cations,e.g., from 0.1 to 10% copper, from 0.1 to 10% magnesium, or both, forexample, based on the total weight of the cations in the substantiallycrystalline (or amorphous sparingly soluble) material. In preferredembodiments the particle comprises at least about 40%, preferably atleast about 60%, and more preferably at least about 80% by weight of oneor more crystalline zinc salts.

Preferred embodiments of the invention comprise particles comprising oneor more of copper hydroxide, alkaline copper carbonate, alkaline copperoxychloride, tribasic copper sulfate, copper borate, or mixturesthereof. The most preferred embodiments of the invention compriseparticles comprising copper hydroxide, alkaline copper carbonate, copperborate, or mixtures thereof.

Coatings for the Copper-Based and Zinc-Based Particulates.

In any of the above-described embodiments, the substantially crystallinecopper composition in copper-based particulates and/or copper-basedparticulate material can further comprise one or more materials disposedon the exterior of the particles to inhibit dissolution of theunderlying substantially crystalline (or amorphous sparingly soluble)copper material at least for a time necessary to prepare the formulationand inject the prepared wood treatment composition. Over time, however,there is unfavorable particle growth via dissolution and precipitationprocesses and also particle growth via agglomeration. Also, theparticulates are very susceptible to premature dissolution if the slurryis formed with an acidic water. In preferred embodiments, either theparticulates containing, for example, alkaline copper carbonate, copperhydroxide, copper borate, alkaline copper nitrate, copper oxychloride,tribasic copper sulfate. Additionally or alternatively the acid-solubleparticles are coated with a substantially inert coating, for example atrace outer coating of e.g. copper phosphate or copper sulfide, or acoating of a polymeric material such as dispersants, or with a thinhydrophobic coating, or any combination thereof. In one embodiment theparticles are treated with a dispersing material which is substantiallybound to the particles.

The milled copper-based, zinc-based, and/or tin-based particlesdescribed above are readily slurried and injected into wood after themilling process. Generally, however, milling is done well before theparticles are slurried and injected. The particles may be shipped in adry form or in a wet form. The milled particles may be transported to asite as a dry mix or as a concentrated slurry, which is then formed intoan injectable slurry, and then after some indeterminate storage time theparticles may be injected into wood. Particulates in solution have atendency to grow over time by 1) the thermodynamically driven tendencyof sub-micron particles in solution to grow by adissolution/reprecipitation process, where there is a greater tendencyfor small particles to slowly dissolve and for the salts toreprecipitate on the larger crystals. It is not uncommon, inunstabilized slurries, for the median particle size to increase by 50%over a period of a day or two. The goal is to simultaneously achieve thecritical particle size, particle size distribution, and particlestability at a cost where the material can be commercially used and atthe point where the material will be commercially used. Therefore, it isadvantageous to have a coating on the particle to substantially hinderdissolution of the particle while the particle is slurried. However, thecoating should not overly hinder dissolution of the particle in the woodmatrix. Further, no coating to hinder dissolution is desirable forcopper oxides particulates.

Inorganic Coating—Generally, the discussion focuses on the preferredcopper-based particulates, but the compositions and methods are equallyapplicable to the zinc-based and tin based particulates. Thesubstantially crystalline (or amorphous sparingly soluble) copper-basedmaterial, zinc-based material, and/or tin-based material can bestabilized by a partial or full coating of an inorganic salt. Themanufacturing process is amenable to the formation of a substantiallyinert inorganic coating on the particle that will be of such lowthickness that the coating will not substantially hinder particledissolution in the wood. The preferred coatings are very low solubilitymetal salts of the underlying metal cations, e.g., copper, zinc, or tin.Exemplary very low solubility salts include copper sulfide (Ksp=6 E-36),copper(II) phosphate (Ksp=1 E-37), and copper 8-quinolinolate (Ksp=2E-30). The selection between sulfide, 8-quinolinolate, and phosphategenerally depends on which coating shows the greatest protection for theparticular substantially crystalline (or amorphous sparingly soluble)material, at the particular size distribution and particle morphologythat may exist. A coating of a very low solubility salt cansubstantially arrest the dissolution/reprecipitation process by severelylimiting the amount of copper that can dissolve. The coating, however,is mechanical protection only. Exposed portions of the underlyingsubstantially crystalline (or amorphous sparingly soluble) copper-,zinc-, or tin-based particulates are subject to dissolution. Further,the inorganic coating is generally at most a few atoms to a fewnanometers in depth.

An inorganic coating can be formed during and immediately after theparticulate precipitation process, for example by adding after admixingthe dissolved copper solution and the dissolved anion solution togetherto form the “precipitation solution”, e.g., after precipitation of thesubstantially crystalline (or amorphous sparingly soluble) particulateshas begun. In one embodiment, the admixed copper-anion solution has asmall excess of anions. Precipitation of the desired copper salts isgenerally fast, but adding a phosphate composition (as acid phosphate,or as a partially neutralized acid phosphate) in an amount to give aconcentration between a few hundred ppm and a few percent by weight willcause a layer of copper sulfate to form, for example, between crystalsor even over the crystals of the substantially crystalline coppermaterial. Alternately, a source of sulfide or 8-quinolinolate can beadded to the precipitation solution. The advantage is the newly formedsubstantially crystalline (or substantially amorphous) material is freshand therefore more reactive toward the added phosphate ions than wouldbe an aged precipitate. This is not a preferred mechanism, however,because during milling some of the coating will be abraded away, andsome previously unexposed substantially crystalline (or amorphoussparingly soluble) material will now be exposed. Additionally, theamount of material used to get the required concentration of anions inthe precipitation solution is much more than is needed to form a coatingon particulates.

The particles may be wet-milled using a very fine milling material and afluid containing a source of sulfate ions, phosphate ions, or lesspreferably (because of odor and handling problems) sulfide ions. In onepreferred embodiment, the wet milling process uses as the milling fluida composition comprising between a few hundred ppm of phosphate to about6% phosphate, for example between 0.1% phosphate to 3% phosphate. Smallamounts of phosphate will take hours or days to form a completelyprotective coating, while a more concentrated solution may form aprotective coating in minutes. Advantageously the milling liquid has apH between about 6 and about 9.5, for example between about 7 and about8.5. This high concentration of phosphate is not wasteful because themilling fluid can be re-used, and also because the milling fluid is arelatively small volume. Such milling in the phosphate-containingmilling fluid, for example for a time ranging from 5 minutes to 4 hours,typically from 10 minutes to 30 minutes, will promote the formation of athin coating of copper phosphate over the substantially crystalline (oramorphous sparingly soluble) copper material. As the coating is probablyonly a few atoms in thickness, the coating will dissolve in good timewithin the wood so as not to impair exposure of the underlyingsubstantially crystalline copper material in the wood. Alternatively, asource of sulfide or 8-quinolinolate can be added to the milling liquid.Sulfide is again not preferred, for safety reasons. If sulfide is addedthe pH should be above 8, preferably above 9. The addition of the8-quinolinolate is not an inorganic coating, and the adherence of acoating of an organic nature may be beneficial.

In another embodiment, the copper-based particles after milling can beexposed to a rinse solution that contains between a few hundred ppm ofphosphate to about 6% phosphate, for example between 0.1% phosphate to3% phosphate. U.S. Pat. No. 4,404,169 describes a process of producingphosphate-stabilized particulates. Phosphate ions are added to asuspension of copper oxychloride in an aqueous phase. The copperoxychloride is then reacted with alkali metal hydroxide or alkalineearth metal hydroxide, and the cupric hydroxide precipitated as a resultof the suspension is washed and then re-suspended and subsequentlystabilized by the addition of acid phosphate to adjust a pH value of 7.5to 9. The suspended copper oxychloride is reacted in the presence ofphosphate ions in an amount of 1 to 4 grams per liter of the suspensionand at a temperature of 20 .degree. C. to 25 .degree. C. and theresulting cupric hydroxide is stabilized with phosphate ions in anamount of 3 to 6 grams per liter of the suspension. Advantageously, therinse liquid has a pH between about 6 and about 9.5, for example betweenabout 7 and about 8.5. After contacting the particles, advantageouslyfor at least a minute or more, this rinse solution can itself be rinsedaway with fresh water. Alternatively, a source of sulfide or8-quinolinolate can be added to the rinse liquid. If sulfide is added,the pH should be above 8, preferably above 9.

In another embodiment, the copper-based particles after milling can beexposed to a rinse solution that contains between a few hundred ppm ofphosphate to about 1% phosphate, for example between 0.1% phosphate to0.5% phosphate ions (by weight of the rinse). After contacting theparticles, advantageously, for at least a minute or more, this rinsesolution can itself be rinsed away with fresh water, and the particlescan be rinsed with a solution comprising a few hundred ppm of solublecopper to about 1% soluble copper, for example between 0.1% phosphate to0.5% soluble copper ions. This copper-containing solution can be rinsedoff with a minimum quantity of water, and the rinsed particulates can bere-exposed to a rinse solution that contains between a few hundred ppmof phosphate to about 1% phosphate, for example, between 0.1% phosphateto 0.5% phosphate ions. Advantageously the fluids have a pH betweenabout 6 and about 9.5, for example between about 7 and about 8.5.

In some embodiments some copper-containing particulates are stabilizedwith a coating, and some particulates are not subject to suchstabilization. For example, advantageously only the very smallparticulates, e.g., smaller than about 0.05 microns in diameter, arestabilized by a low solubility covering layer.

The invention also embraces embodiments where particles aresubstantially free of an inorganic coating.

Organic Coating—Copper-based particles (or zinc-based particles, ortin-based particles, or mixtures thereof) of the invention may be useddirectly to preserve wood or wood products. The copper-based,zinc-based, or tin-based particles or mixtures thereof may additionallycomprise an organic coating, e.g., an organic layer that partially orcompletely covers the exterior surface area of the particulates. Theprotective organic layer may additionally function as one or more otheractive agents, as discussed infra. This organic coating can comprise avariety of materials having a variety of functions over and above beingan organic layer acting as a protective layer temporarily isolating thesparingly soluble salt from the aqueous carrier to slow dissolution ofparticulates in the slurry, including: 1) an organic biocide carrier, 2)a dispersing/anti-aggregation/wettability modifying agent, 3) one ormore biocides, or any combinations thereof. The oil coating can comprisefor example light oils, dehydrating oils, polymeric films, organicbiocides, disbursing agents, anti-coagulating agents, or mixturesthereof.

In one embodiment, at least some of the particulates are coated with anorganic protective coating. The particulates may have been previouslycoated with an inorganic coating. The organic coating should provide athin layer of organic material that at least partially coats theparticulate and for a period of time reduces the tendency of thesparingly soluble copper, zinc, and/or tin salts in the particulates todissolve in the slurry.

Generally such coatings are extremely thin, with a particulatecomprising, for example, between about 0.1% to about 50% by weight, moretypically from about 0.5% to about 10%, of the weight of theabove-mentioned sparingly soluble salts. The coating may cover only aportion of the exterior surface area, for example only 50% of theexternal surface area of a particulate.

The hydrocarbon composition can include one or more hydrophobic oils,and/or may comprise an organic compound having one or more polarfunctional groups which increase adherence of, for example, mono- and/orpoly-carboxylic acids that may be at least partially neutralized with ametal such as a fatty acid or a polycarylic polymer, a surfactant and/ora disbursing agent, amphoteric agents, an organic biocide including anamine, azole, triazole, or any other organic biocides, a film-formingpolymer such as a sulfonated ionomer, or mixtures thereof. These andother organic and/or organometallic components that form an organiclayer will generally be referred to as a “hydrocarbon layer” or“hydrocarbon composition.”

An organic coating may be formed by contacting particulates with ahydrocarbon composition containing the materials to be deposited ontothe exterior surface of the particle. The contacting may occur in aslurry or may be done with a paste of water-wetted particulates or maybe done with dried particulates. The less free water, the easier it isto promote adherence between the hydrocarbon composition to theparticulates.

Heating a mixture of particulates and the hydrocarbon composition willalso help the hydrocarbon composition wet and adhere to theparticulates. Advantageously, in one embodiment most of the solvent ofthe hydrocarbon composition is volatile and is removed prior toinjection of the particulates into the wood. This will leave a thinlayer of a more concentrated biocide in heavier oils and/or binders thanwas found in the hydrocarbon/biocide composition. The organic coatinggenerally becomes more adherent if the coated particulates are allowedto age, and/or are subjected to heat, for example, to 35° C. or abovefor a period of an hour, for example.

Incorporating some solvents, typically polar solvents, e.g., at least10%, for example, at least 30% or at least 50% by weight of solventssuch as one or more of alcohols, amides, ketones, esters, ethers,glycols, and such into the particulates may help the hydrocarbon layercomposition wet the particulates, and will allow thinner hydrocarbonlayers to be deposited. Solvents are lower molecular weight and highervolatility than oils, and solvents may be stripped from the organiccoating before slurrying the particles or during kiln drying of thewood. The hydrocarbon composition may therefore comprise optionalsolvents and/or diluents, for example, a mixture of an oily or oil-typeorganochemical compound and a solvent of low volatility and/or a polarorganochemical solvent or solvent mixture. Organochemical oils which arepreferably employed are oily or oil-type solvents with an evaporationnumber of above 35 and a flash point of above 30° C., preferably above45° C. Such water-insoluble, oily and oil-type solvents of lowvolatility which are used are suitable mineral oils or their aromaticfractions or mineral-oil containing solvent mixtures, preferably whitespirit, petroleum and/or alkyl benzene. Mineral oils include those witha boiling range of from 170 to 220° C., spindle oil with a boiling rangeof from 250 to 350 v, petroleum and aromatics with a boiling range offrom 160 to 280° C., oil of turpentine and the like. In one embodiment,liquid aliphatic hydrocarbons with a boiling range of from 180 to 210°C. or high-boiling mixtures of aromatic and aliphatic hydrocarbons witha boiling range of 180 to 220° C. and/or spindle oil and/ormonochloronaphthalene are used, for example, a monochloronaphthalene.The organic oily or oil-type solvents of low volatility and with anevaporation number of above 35 and a flash point of above 30° C.,preferably above 45° C., can be replaced in part by organochemicalsolvents of high or medium volatility, with the proviso that thepreferred solvent mixture also has an evaporation number of above 35 anda flashpoint of above 30° C., preferably 45° C., and that the biocidesand/or other compounds are soluble or emulsifiable in this solvent/oilmixture. In one embodiment, aliphatic organochemical solvents whichcontain hydroxyl and/or ester and/or ether groups are used, such as, forexample, glycol ethers, esters or the like. Advantageously thehydrocarbon mixture comprises binders to wet and adhere to theparticulate, for example, synthetic resins binding drying oils includinglinseed oil, and also binders comprising, an acrylate resin, a vinylresin, for example polyvinyl acetate, polyester resin, polycondensationor polyaddition resin, polyurethane resin, alkyd resin or modified alkydresin, preferably of medium oil length, phenol resin, hydrocarbon resinsuch as indene/coumarone resin, silicone resin, drying vegetable and/ordrying oils and/or physically drying binders based on a natural and/orsynthetic resin. Pertinent agricultural drying oils include linseed,soybean, canola, rapeseed, sunflower, tung and castor oils.

This organic coating can comprise a variety of materials having avariety of functions, including, but not limited to, surface-activeagents and organic biocides.

Surface-Active Agents—Agents improving the suspension of theparticulates include dispersants such as phenyl sulfonates,alkylnaphthalene sulfonates and polymerized naphthalene sulfonates,polyacrylic acids and their salts, polyacrylamides, polyalkoxydiaminederivatives, polyethylene oxides, polypropylene oxide, polybutyleneoxide, taurine derivatives and their mixtures, and sulfonated ligninderivatives. Surfactants include anionic surfactants, cationicsurfactants, nonionic surfactants, or combinations thereof.Polyethyleneimine can act as a surfactant or a stabilizer and will alsochelate copper. Dispersants can be used at 0.1% to 50%, preferably 0.5%to 20% or 5-10% of the particulate product.

Organic Biocides—As previously stated, the particles may be combinedwith one or more additional moldicides or more generally biocides, toprovide added biocidal activity to the wood or wood products. Preferredpreservative treatments comprise copper-based particles having one ormore additional organic biocide(s) that are bound, such as byadsorption, to a surface of the particles. Wood and wood products may beimpregnated substantially homogeneously with (a) copper-based particlesof the invention and (b) a material having a preservative function, suchas a material bound to the surface of the copper-based particles. Bysubstantially homogeneously we mean averaged over a volume of at leastone cubic inch, as on a microscopic scale there will be volumes havingparticulates disposed therein and other volumes within the wood that donot have particulates therein. Thus, the distribution of preservativefunction within the wood or wood product is preferably notheterogeneous.

The absolute quantity of organic biocides is very low. In general, thebiocides are present in a use concentration of from 0.1% to 20%,preferably 1% to 5%, based on the weight of the copper salts. Thesparingly soluble copper-salt particulates of this invention aretypically expected to be added to wood in an amount equal to or lessthan 0.25 pounds as copper per cubic foot. The organic biocide(s) at a4% loading relative to the copper are present at about 0.16 ounces orabout 3 to 4 milliliters of biocide per cubic foot. The organic biocidesare often insoluble in water, which is the preferred fluid carrier forinjecting the wood preservative treatment into wood, so getting adequatedistribution of the biocide within the wood matrix is problematic. Inprior art formulations, the wood preservative may be, for example,admixed in a large excess of oil, and the oil emulsified with water andadmixed with the soluble copper for injection into the wood. Problemsarise if the injection is delayed, or if the slurry has compounds whichbreak the emulsion, and the like.

The greatest benefit is that a portion or all of the organic biocidesincorporated into the wood preservative treatment can advantageously becoated on to the particulates. By adhering the biocides on particulates,a more even distribution of biocide in ensured, and the copper isdisposed with the biocide and therefore is best positioned to protectthe biocide from those bio-organisms which may degrade or consume thebiocide. Finally, a formulation with biocide adhering to particulatesdoes not face the instability problems that emulsions face.

Generally, so little of the organic biocide is needed that it isdissolved in and diluted with sufficient hydrocarbon material to makethe phase of appreciable size. The organic material/biocide mixture canbe contacted with particulates in a slurry, though it may be difficultto have the hydrocarbon phase adhere to the particulates. Pretreatingthe particulates with a coating of for example 8-quinolinolate willgreatly increase the likelihood of the biocide absorbing on theparticulate. The particulates may be concentrated, for example, to an atleast 40% by weight particulates in water slurry before admixing in withthe hydrocarbon/biocide composition.

The biocides can be any of the known organic biocides. Exemplarymaterials having a preservative function include materials having atleast one of one or more: azoles; triazoles; imidazoles; pyrimidinylcarbinoles; 2-amino-pyrimidines; morpholines; pyrroles; phenylamides;benzimidazoles; carbamates; dicarboximides; carboxamides;dithiocarbamates; dialkyldithiocarbamates;N-halomethylthio-dicarboximides; pyrrole carboxamides; oxinecopper,guanidines; strobilurines; nitrophenol derivatives; organo phosphorousderivatives; polyoxins; pyrrolethioamides; phosphonium compounds;polymeric quaternary ammonium borates; succinate dehydrogenaseinhibitors; formaldehyde-releasing compounds; naphthalene derivatives;sulfenamides; aldehydes; quaternary ammonium compounds; amine oxides,nitrosoamines, phenol derivatives; organo-iodine derivatives; nitrites;quinolines such as 8-hydroxyquinoline including their Cu salts;phosphoric esters; organosilicon compounds; pyrethroids; nitroimines andnitromethylenes; and mixtures thereof.

Exemplary biocides include Azoles such as azaconazole, bitertanol,propiconazole, difenoconazole, diniconazole, cyproconazole,epoxiconazole, fluquinconazole, flusiazole, flutriafol, hexaconazole,imazalil, imibenconazole, ipconazole, tebuoonazole, tetraconazole,fenbuconazole, metconazole, myclobutanil, perfurazoate, penconazole,bromuconazole, pyrifenox, prochloraz, triadimefon, triadlmenol,triffumizole or triticonazole; pyrimidinyl carbinoles such as ancymidol,fenarimol or nuarimol; chlorothalonil; chlorpyriphos;N-cyclohexyldiazeniumdioxy; dichlofluanid; 8-hydroxyquinoline (oxine);isothiazolone; imidacloprid; 3-iodo-2-propynylbutylcarbamatetebuconazole; 2-(thiocyanomethylthio)benzothiazole (Busan 30);tributyltin oxide; propiconazole; synthetic pyrethroids;2-aminopyrimidines such as bupirimate, dimethirimol or ethirimol;morpholines such as dodemorph, fenpropidin, fenpropimorph, spiroxanin ortridemorph; anilinopyrimdines such as cyprodinil, pyrimethanil ormepanipyrim; pyrroles such as fenpiclonil or fludioxonil; phenylamidessuch as benalaxyl, furalaxyl, metalaxyl, R-metalaxyl, ofurace oroxadixyl; benzimidazoles such as benomyl, carbendazim, debacarb,fuberidazole or thiabendazole; dicarboximides such as chlozolinate,dichlozoline, iprdine, myclozoline, procymidone or vinclozolin;carboxamides such as carboxin, fenfuram, flutolanil, mepronil,oxycarboxin or thifluzamide; guanidines such as guazatne, dodine oriminoctadine; strobilurines such as azoxystrobin, kresoxim-methyl,metominostrobin, SSF-129, methyl2-[(2-trifluoromethyl)pyrid-yloxymethyl]-3-methoxycacrylate or2-[.alpha.{[(.alpha.-methyl-3-trifluoromethyl-benzyl)imino]oxy}-o-toly]glyoxylicacid-methylester-o-methyloxime (trifloxystrobin); dithiocarbamates suchas ferbam, mancozeb, maneb, metiram, propineb, thiram, zineb, or ziram;N-halomethylthio-dicarboximides such as captafol, captan, dichlofluanid,fluorormide, folpet or tolfluanid; nitrophenol derivatives such asdinocap or nitrothal-isopropyl; organo phosphorous derivatives such asedifenphos, iprobenphos, isoprothiolane, phosdiphen, pyrazophos ortoclofos-methyl; and other compounds of diverse structures such asaciberolar-S-methyl, anilazine, blasticidin-S, chinomethionat,chloroneb, chlorothalonil, cymoxanil, dichlone, dicomezine, dicloran,diethofencarb, dimethomorph, dithianon, etridiazole, famoxadone,fenamidone, fentin, ferimzone, fluazinam, flusuffamide, fenhexamid,fosetyl-alurinium, hymexazol, kasugamycin, methasuifocarb, pencycuron,phthalide, polyoxins, probenazole, propamocarb, pyroquilon, quinoxyfen,quintozene, sulfur, triazoxide, tricyclazole, triforine, validamycin,(S)-5-methyl-2-methylthio-5-phenyl-3-phenylamino-3,5-dihydroimidazol-4-one(RPA 407213),3,5-dichloro-N-(3-chloro-1-ethyl-1-methyl-2oxopropyl)-4-methylbenzamide(RH7281), N-alkyl-4,5-dimethyl-2-timethylsilylthiophene-3-carboxamide(MON 65500),4-chloro-4-cyano-N,N-dimethyl-5-p-tolylimidazole-1-sulfonamide(IKF-916),N-(1-cyano-1,2-dimethylpropyl)-2-(2,4-dichlorophenoxy)-propionamide (AC382042), or iprovalicarb (SZX 722). Also included are the biocidesincluding pentachlorophenol, petroleum oils, phenothrin, phenthoate,phorate, as well as trifluoromethylpyrrole carboxamides andtrifluoromethylpyrrolethioamides described in U.S. Pat. No. 6,699,818;Triazoles such as amitrole, azocylotin, bitertanol, fenbuconazole,fenchlorazole, fenethanil, fluquinconazole, flusilazole, flutriafol,imibenconazole, isozofos, myclobutanil, metconazole, epoxyconazole,paclobutrazol,(±)-cis-1-(4-chlorophenyl)-2-(1H-1,2,4-triazol-1-yl)-cycloheptanol,tetraconazole, triadimefon, triadimenol, triapenthenol, triflumizole,triticonazole, uniconazole and their metal salts and acid adducts;Imidazoles such as Imazalil, pefurazoate, prochloraz, triflumizole,2-(1-tert-butyl)-1-(2-chlorophenyl)-3-(1,2,4-triazol-1-yl)-propan-2-ol,thiazolecarboxanilides such as2′,6′-dibromo-2-methyl-4-trifluoromethoxy-4′-trifluoromethyl-1,3-thiazole-5-carboxanilide;fungicides such as azaconazole, bromuconazole, cyproconazole,dichlobutrazol, diniconazole, hexaconazole, metconazole, penconazole,epoxyconazole, methyl(E)-methoximino[a-(o-tolyloxy)-otoly)]acetate,methyl(E)-2-{2-[6-(2-cyanophenoxy)-pyrimidin-4-yl-oxy]phenyl}-3-methoxyacrylate-,methfuroxam, carboxin, fenpiclonil,4(2,2-difluoro-1,3-benzodioxol-4-yl)-1Hpyrrole-3-carbonitrile,butenafine, and 3-iodo-2-propynyl-n-butylcarbamate (IPBC); triazolessuch as described in U.S. Pat. Nos. 5,624,916, 5,527,816, and 5,462,931;the biocides described in U.S. Pat. No. 5,874,025;5-[(4-chlorophenyl)methyl]-2,2-dimethyl-1-(1H-1,2,4-triazol-1-yl-methyl)cyclopentanol;Methyl(E)-2-[2-[6-(2-cyanophenoxyl)pyrimidin-4-yloxy]phenyl]3-methoxyacrylate;methyl(E)-2-[2-[6-(2-thioamidophenoxyl)pyrimidin-4-yloxy]phenyl]-3-methoxyacrylate;methyl(E)-2-[2-[6-(2-fluorophenoxyl)pyrimidin-4-yloxy]phenyl]-3-methoxyacrylate;methyl(E)-2-[2-[6-(2,6-difluorophenoxyl)pyrimidin-4-yloxy]phenyl]-3-methoxyacrylate;methyl(E)-2-[2-[3-(pyrimidin-2-yloxy)phenoxy]phenyl]-3-methoxyacrylate;methyl(E)-2-[2-[3-(5-methylpyrimidin-2-yloxy)-phenoxy]phenyl]-3-methoxyacrylate;methyl(E)-2-[2-[3-(phenylsulphonyloxy)phenoxy]phenyl]-3-methoxyacrylate,methyl(E)-2-[2-[3-(4-nitrophenoxyl)phenoxy]phenyl]-3-methoxyacrylate-;methyl(E)-2-[2-phenoxyphenyl]-3-methoxyacrylate;methyl(E)-2-[2-(3,5-dimethylbenzoyl)pyrrol-1-yl]-3-methoxyacrylate;methyl(E)-2-[2-(3-methoxyphenoxyl)phenyl]-3-methoxyacrylate;methyl(E)-2[2-(2-phenylethen-1-yl)-phenyl]-3-methoxyacrylate;methyl(E)-2-[2-(3,5-dichlorophenoxy) pyridin-3-yl]-3-methoxyacrylate;methyl(E)-2-(2-(3-(1,1,2,2tetrafluoroethoxy)phenoxy)phenyl)-3-methoxyacrylate;methyl(E)-2-(2-[3-(alphahydroxybenzyl)phenoxy]phenyl)-3-methoxyacrylate;methyl(E)-2-(2-(4-phenoxypyridin2-yloxy)phenyl)-3-methoxyacrylate;methyl(E)-2-[2-(3-n-propyloxyphenoxy)phenyl]-3-methoxyacrylate;methyl(E)-2-[2-(3-isopropyloxyphenoxyl)phenyl]-3-methoxyacrylate;methyl(E)-2-[2-[3-(2-fluorophenoxyl) phenoxy]phenyl]-3-methoxyacrylate;methyl(E)-2-[2-(3ethoxyphenoxy)phenyl]-3-methoxyacrylate;methyl(E)-2-[2-(4-tert-butylpyridin-2-yloxy)phenyl]-3-methoxyacrylate;methyl(E)-2-[2-[3-(3-cyanophenoxyl)phenoxy]phenyl]-3-methoxyacrylate;methyl(E)-2-[2-[(3-methylpyridin-2-yloxymethyl)phenyl]-3-methoxyacrylate;methyl(E)-2-[2-[6-(2-methylphenoxyl)pyrimidin-4-yloxy]phenyl]-3-methoxyacrylate;methyl(E)2-[2-(5-bromopyridin-2-yloxymethyl)phenyl]-3-methoxyacrylate;methyl(E)-2-[2-(3-(3iodopyridin-2-yloxy)phenoxy)phenyl]-3-methoxyacrylate;methyl(E)-2-[2-[6-(2-chloropyridin-3-yloxy)pyrimidin-4-yloxy]phenyl]-3-methoxyacrylate;(E),(E)-methyl-2-[2-(5,6-dimethylpyrazin2-ylmethoximinomethyl)phenyl]-3-methoxyacrylate;(E)-methyl-2-{2-[6-(6-methylpyridinyloxyl)pyrimidin-4-yloxy]phenyl}-3-methoxyacrylate;(E),(E)-methyl-2-{2-[(3-methoxyphenyl)methyloximinomethyl]phenyl}-3-methoxyacrylate;(E)-methyl-2-{2-[(6-(2azidophenoxy)-pyrimidin-4-yloxy]phenyl}-3-methoxyacrylate;(E),(E)-methyl-2-{2-[(6-phenylpyrimidin-4-yl)-methyloximinomethyl]-phenyl}-3-methoxyacrylate;(E),(E)-methyl-2-{2-[(4-chlorophenyl)-methyloximinomethyl]phenyl}-3-methoxyacrylate;(E)-methyl-2-{2-[6-(2-npropylphenoxy)-1,3,5-triazin-4-yloxy]phenyl}-3-methoxyacrylate;(E),(E)-methyl-2-{2-[(3-nitrophenyl)methyloximinomethyl]phenyl}-3-methoxyacrylate;Succinate dehydrogenase inhibitors such as Fenfuram, furcarbanil,cyclafluramid, furmecyclox, seedvax, metsulfovax, pyrocarbolid,oxycarboxin, shirlan, mebenil (mepronil), benodanil, and flutolanil;Benzimidazoles, such as carbendazim, benomyl, furathiocarb,fuberidazole, thiophonatmethyl, thiabendazole or their salts; Morpholinederivatives, such as tridemorph, fenpropimorph, falimorph, dimethomorph,dodemorph; aldimorph, fenpropidine and their arylsulphonates, such as,for example, p-toluenesulphonic acid and p-dodecylphenylsulphonic acid;Benzothiazoles, such as 2-mercaptobenzothiazole; Benzamides, such as2,6-dichloro-N-(4-trifluoromethylbenzyl)-benzamide; Formaldehyde andformaldehyde-releasing compounds, such as benzyl alcoholmono(poly)-hemiformal, oxazolidine, hexa-hydro-S-triazines,Nmethylolchloroacetamide, paraformadehyde, nitropyrin, oxolinic acid,tecloftalam; Tris-N(cyclohexyldiazeneiumdioxy)-aluminium;N-(cyclohexyldiazeneiumdioxy)-tributyltin; N-octylisothiazolin-3-one;4,5-trimethylene-isothiazolinone; 4,5-benzoisothiazolinone;Nmethylolchloroacetamide; Pyrethroids, such as allethrin, alphamethrin,bioresmethrin, byfenthrin, cycloprothrin, cyfluthrin, decamethrin,cyhalothrin, cypermethrin, deltamethrin,alpha-cyano-3-phenyl-2-methylbenzyl2,2-dimethyl-3-(2-chloro-2-trifluoromethylvinyl)cyclopropane-carboxylate,fenpropathrin, fenfluthrin, fenvalerate, flucythrinate, flumethrin,fluvalinate, permethrin, resmethrin and tralomethrin; Nitroimines andnitromethylenes, such as1-[(6-chloro-3-pyridinyl)-methyl]-4,5-dihydro-N-nitro-1H-imidazol-2-amine(imidacloprid), andN-[(6-chloro-3-pyridyl)methyl]-N2-cyano-NJ-methylacetamide (N125);Quaternary ammonium compounds, such as didecyldimethylammonium salts,benzyldimethyltetradecylammonium chloride, benzyldimethyldodecylammoniumchloride, and didecyldimethaylammonium chloride; Phenol derivatives,such as tribromophenol, tetrachlorophenol, 3-methyl-4-chlorophenol,3,5-dimethyl-4-chlorophenol, phenoxyethanol, dichlorophene,o-phenylphenol, m-phenylphenol, p-phenylphenol, 2-benzyl-4-chlorophenoland their alkali metal and alkaline earth metal salts; iodinederivatives, such as diiodomethyl p-tolyl sulphone, 3-iodo-2-propynylalcohol, 4-chloro-phenyl-3-iodopropargyl formal,3-bromo-2,3diiodo-2-propenyl ethylcarbamate, 2,3,3-triiodoallyl alcohol,3-bromo-2,3-diiodo-2-propenyl alcohol, 3-iodo-2-propynyln-butylcarbamate, 3-iodo-2-propynyl n-hexylcarbamate, 3-iodo-2-propynylcyclohexylcarbamate, 3-iodo-2-propynyl phenylcarbamate; Microbicideshaving an activated halogen group, such as chloroacetamide, bronopol,bronidox, tectamer, such as 2bromo-2-nitro-1,3-propanediol,2-bromo-4′-hydroxyacetophenone, 2,2-dibromo-3-nitrilepropionamide,1,2-dibromo-2,4-dicyanobutane, .beta.-bromo-.beta.-nitrostyrene; andcombinations thereof. These are merely exemplary of a few classes of theknown and useful biocides, and the list could easily extend for pages.

The preferred biocides are oil-soluble, and include quaternary ammoniumcompounds including, for example, didecyldimethylammonium salts;azoles/triazoles including, for example, N-alkylated tolytriazoles,metconazole, imidacloprid, hexaconazole, azaconazole, propiconazole,tebuconazole, cyproconazole, bromoconazole, and tridemorph tebuconazole;moldicides; HDO available commercially by BASF, or mixtures thereof.Biocides such as tebuconazole are quite soluble in common organicsolvents, while others such as chlorothalonil possess only lowsolubility.

To apply the biocide to particulates, the biocide/hydrocarboncomposition is admixed, taking care that the biocide is dispersed andpreferably solubilized in the hydrocarbon composition. Thebiocide/hydrocarbon composition can be prepared in a manner known perse, for example, by mixing the active compounds with the solvent ordiluent, emulsifier, dispersant and/or binder or fixative, waterrepellant, and, if appropriate, dyes and pigments and other processingauxiliaries. Then, the biocide/hydrocarbon composition is admixed withparticulates, where the particulates can be suspended in a slurry, bewet, or be dry. The composition is mixed to aid the wetting of anddistribution of the biocide/hydrocarbon composition to particulates. Thecomposition may be heated, for example to about 40° C., and is alsobeneficially allowed to sit for a period ranging from minutes to hours.The mixture can then be incorporated into a slurry or be dried orformulated into a stable concentrated slurry for shipping.

In an alternative embodiment, the biocide/hydrocarbon composition isapplied as a spray or aerosol onto individual particles, such asparticles suspended in a gas stream. These coated particulates are thentreated to prevent coalescence by, for example, drying the oil to removetackiness, or coating the particle with other adjuvants such asanticoagulants, wettability agents, dispersibility agents, and the like.Such a product can be stored, shipped, and sold as a dry pre-mix.

In another embodiment, the particles are wetted with a light hydrocarbonmaterial, which mayor may not contain biocide, and the hydrocarbonmaterial is then substantially removed by washing or drying, leaving avery thin layer of hydrocarbon residue that may range, for example, from1 to 30 nanometers thick. Such a very thin layer will have negligibletackiness and negligible weight, but will protect the particulate fromdissolution and will discourage coagulation in the slurry.

Alternate Organic Biocide Carrier—In another embodiment, only a fractionof the particulates, be they copper-based, zinc-based, or tin-based, maybe coated with the hydrocarbon/biocide combination. Some precipitationtechniques are known to produce salts having high porosity, and thesehigh porosity salts can absorb a substantial quantity of the biocidetherein without forming a tacky coating.

In another embodiment, the organic biocide/hydrocarbon composition iscontacted with a porous inert particulate carrier, for example 0.1micron in diameter high porosity alumina, silica, zeolites, diatomaceousearth, attapulgite clay, or the like. Such material is readilyavailable. For example, U.S. Pat. No. 5,527,423 disclosed alumina with amaximum particle size below 0.3 microns, having high porosity asevidenced by a BET surface area of several hundred square meters pergram, and shows this material can be made into a stable slurry.Preferred zeolites include Ag, Zn or Cu-containing zeolites, whichthemselves have a biocidal activity. These carrier materials areinexpensive, they do not contribute bio-nourishment as does thepolymeric nanoparticles, and the rigidalumina/silica/zeolite/diatom/clay particulates will hold the biocideswithin the pores thereof during preparation of the slurry and injectionof the slurry, or for example during admixing with glue and/or resins tomake wood composites. Therefore, such inert carrier/organic biocideparticulates and, additionally or alternatively, biocidalzeolite/organic biocide particulates would be useful even with thesoluble copper wood preservative treatments in commercial use today.Such particulates advantageously have a solid, typically insoluble,crystalline structure that is advantageously between about 0.01 to about0.3 microns in average diameter, for example, between about 0.05 toabout 0.2 microns in average diameter. A method of manufacturing saidparticulates is to pull a vacuum on a quantity of dry carrier material,and then introduce thereto a composition comprising a major portion(e.g., 50% to 90%) of solvent(s), advantageously a minor portion (e.g.,5% to 48%) of oil(s), and including between 1% and 40% of organicbiocides. The composition is mixed with the inert carrier and pressuremay be exerted to fill the pores of the inert carrier material with thecomposition. Then, the solvents and optionally some of the oils may beremoved by drying, heat, or by vacuum. Assuming 30% effective porosityin an alumina carrier is filled to one third with a hydrocarbon/biocidecomposition having 20% by weight of biocide, the total amount of biocidecarrier material needed to treat 100 cubic feet of wood would be about 1to 2 cups of alumina. Beneficially, organic biocide is slowly leachedfrom the particulates. The biocide formulation in an inert particulatecarrier advantageously comprises oils to help transport biocide from thecenter of the particulate to the exterior of the particulate, and/or mayinclude binders to increase the tenacity of the biocide to theparticulates. These particulates will protect the biocide dispersedwithin the pores thereof, and will reduce the leach rate of the biocide.These particulates are an improvement over emulsions in that they ensurea stable formulation and uniform dispersion of the organic biocides inwood. The carrier material, for example alumina, can be milled with thesame equipment used to mill the copper salt containing particulates.These biocide-containing polymers can then be slurried with thecopper-based particulates of the current invention and both solids canbe injected. The advantage of this process is that the carrier, forexample, alumina, can be separately prepared and treated so that thealumina will not be tacky, by, for example, driving off the lighter oilsand leaving only a very thin layer of biocide within the pores of thecarrier. A second advantage is that the alumina/biocide can be used as afiller in a premix, thereby encouraging mixing properties.

An exemplary preservative of the invention comprises a flowable materialcomprising copper-based particles of the invention. Exemplary flowablematerials include liquids, emulsions, slurries, and suspensions.

In one embodiment, a preservative of the invention comprises one or morematerials additional to the copper-based particles, the additionalmaterials preferably also providing a preservative function. Forexample, an exemplary preservative comprises an emulsion comprising thecopper-based particles, where at least one phase of the emulsion maycomprise one or more materials having a preservative function. Exemplarymaterials having a preservative function include materials having atleast one of one or more triazole groups, one or more quaternary aminegroups, and one or more nitroso-amine group. Mixtures of these materialsmay be used. Preferred preservative materials inhibit organisms that maybe resistant to copper-based preservatives. Biocides useful in wood orwood product preservation are preferred materials. Preferredpreservatives comprise copper-based particles comprising one or morematerials having a preservative function that are bound, such as byadsorption, to a surface of the particles. Wood and wood products may beimpregnated substantially homogeneously with (a) copper based particlesof the invention and (b) a material having a preservative function, suchas a material bound to the surface of the copper-based particles. Thus,the distribution of preservative function within the wood or woodproduct is made more heterogeneous by being absorbed onto theparticulates.

Finally, in one embodiment the wood preservative treatment may comprisea portion of the organic biocide coated on the copper-based particulatesand another portion of the organic biocide with a particulate inertcarrier. The carrier particulates containing organic biocides and/or thecopper-based particulates may be treated to reduce tackiness.

Injectable Slurry

In a variation of the invention, the slurry comprises: a liquid carrier;injectable solid particulates comprising one or more organic biocides;and one or more soluble copper salts or complexes including the solublecopper treatments described in the prior art. The injectableparticulates can be copper-based particulates, zinc-based particulates,tin-based particulates, inert carrier-based particulates, bioactivezeolite-based particulates, or mixtures thereof. The particulates inthis variant of the invention are primarily carriers for the organicbiocides. An exemplary particle comprises copper hydroxide having anaverage particle diameter of less than about 500 nanometers, for exampleless than about 250 nanometers, or less than about 200 nanometers, asmeasured by Stokes Law. Preferably, the average particle diameter is atleast 25 nanometers, for example, at least 50 nanometers. In oneembodiment of the invention, the particles have a surface area of atleast about 10 m²/gram of particles, for example, at least about 40m²/gram of particles, for example, at least about 75 m²/gram ofparticles, for example about 80 m²/gram of particles. The particle sizedistribution of the particulates in one embodiment is such that at leastabout 30% by weight of the particulates have an average diameter betweenabout 0.07 microns and about 0.5 microns, or preferably at least about50% by weight of the particulates have an average diameter between about0.1 microns and about 0.4 microns.

In another variation of the invention the slurry comprises: a liquidcarrier; injectable solid particulates comprising a slightly solublecopper salt; and particulates comprising metallic copper and/or zinc. Anexemplary particle having an average particle diameter of less thanabout 500 nanometers, for example, less than about 250 nanometers, orless than about 200 nanometers, as measured by Stokes Law, and theaverage particle diameter is at least 25 nanometers, for example, atleast 50 nanometers. The particle size distribution of the particulatesin one embodiment is such that at least about 30% by weight of theparticulates have an average diameter between about 0.02 microns andabout 0.4 microns, or preferably at least about 50% by weight of theparticulates have an average diameter between about 0.05 microns andabout 0.3 microns. The metallic copper and/or metallic zinc particulateshave both a minor biocidal effect and also an anti-corrosion effect. Theamount of metal, either copper, zinc, or both, in the anticorrosionmetallic particulates can range from about 1 part to about 25 parts per100 parts of particulates comprising slightly soluble copper salts. Themetal-containing particulates in this variant of the invention areprimarily anti-corrosion additives, though they will have some biocidaleffect. Further, organic biocides can be readily coated onto thesemetal-containing particulates. In one embodiment of this variant, theslurry comprises: A) a liquid carrier; B) injectable solid particulatescomprising metallic copper and/or metallic zinc and also one or moreorganic biocides, and either C-1) one or more soluble copper salts orcomplexes including the soluble copper treatments described in the priorart, C-2) one or more injectable particulates comprising slightlysoluble salts of copper and/or zinc, or C-3) both.

The copper-based particulates can comprise or consist essentially of anysparingly soluble substantially crystalline (or sparingly solubleamorphous) copper salts. In one embodiment the substantially crystalline(or amorphous sparingly soluble) copper salts in the copper-basedparticulates comprise or consist essentially of one or more copper saltsselected from copper hydroxides; copper carbonates (e.g., “yellow”copper carbonate); basic (or “alkaline”) copper carbonates; basic coppersulfates including particularly tribasic copper sulfate; basic coppernitrates; copper oxychlorides (basic copper chlorides); copper borates;basic copper borates; copper ferricyanate; copper fluorosilicate; copperthiocyanate; copper diphosphate or copper pyrophosphate, copper cyanate;and mixtures thereof. In one embodiment, the copper based particlescomprise a substantially crystalline copper compound. At least about20%, 30%, 50%, or 75% of the weight of the copper-based particles may becomposed of the substantially crystalline copper compound(s).

In a preferred embodiment, the substantially crystalline (or amorphoussparingly soluble) copper salts in the copper-based particulatescomprise or consist essentially of one or more copper salts selectedfrom copper hydroxides; copper carbonates, basic (or “alkaline”) coppercarbonates; basic copper sulfates including particularly tribasic coppersulfate; basic copper nitrates; copper oxychlorides (basic copperchlorides); copper borates, basic copper borates, and mixtures thereof.In one embodiment, the copper-based particles comprise a substantiallycrystalline copper compound. At least about 20%, 30%, 50%, or 75% of theweight of the copper-based particles may be composed of thesubstantially crystalline copper compound.

In another embodiment the substantially crystalline (or amorphoussparingly soluble) copper salts in the copper-based particulates in awood preservative formulation can comprise or consist essentially of aplurality of sparingly soluble substantially crystalline (or amorphoussparingly soluble) copper salts selected from copper oxide, copperhydroxides; copper carbonates, alkaline (or “basic”) copper carbonates;alkaline copper sulfates; alkaline copper nitrates; copper oxychlorides;copper borates, basic copper borates, and mixtures thereof, with theproviso that at least one of the substantially crystalline (or amorphoussparingly soluble) copper salts is not a copper oxide. Of the copperoxides, Cu₂O is preferred over CuO. In a variant of this, thecopper-based particulate material can comprise or consist essentially ofone or more sparingly soluble substantially crystalline copper saltsselected from copper hydroxides; copper carbonates, alkaline (or“basic”) copper carbonates; alkaline copper nitrates; alkaline coppersulfates; copper oxychlorides; copper borates, basic copper borates, andmixtures thereof. In one embodiment, the copper-based particles comprisea substantially crystalline copper compound. At least about 20%, 30%,50%, or 75% of the weight of the copper-based particles may be composedof the substantially crystalline copper compound(s).

In any of the above, the substantially crystalline (or amorphoussparingly soluble) copper composition can have a substantial amount ofone or more of magnesium, zinc, or both, wherein these cations areeither dispersed within the substantially crystalline (or amorphoussparingly soluble) copper composition, or be a separate phase within aparticulate. In preferred embodiments of the invention, at least someparticulates comprise copper hydroxide, basic copper carbonate, or both.In more preferred embodiments, the copper hydroxide comprises between 6and 20 parts of magnesium per 100 parts of copper, for example between 9and 15 parts of magnesium per 100 parts of copper. Alternatively, inanother more preferred embodiments, the copper hydroxide comprisesbetween 6 and 20 parts total of magnesium and zinc per 100 parts ofcopper, for example between 9 and 15 parts total of magnesium and zincper 100 parts of copper. In some embodiments, the basic copper carbonatecomprises between 6 and 20 parts of magnesium per 100 parts of copper,for example between 9 and 15 parts of magnesium per 100 parts of copper,or alternatively between 6 and 20 parts total of magnesium and zinc per100 parts of copper, for example between 9 and 15 parts total ofmagnesium and zinc per 100 parts of copper. Alternatively oradditionally, in a preferred embodiment, the copper hydroxide and/orbasic copper carbonate comprises between about 0.01 and about 5 parts ofphosphate per 100 parts of copper, for example between 9 and 15 parts ofphosphate per 100 parts of copper.

In another preferred embodiment, the slurry comprises a sparinglysoluble copper salt particulates and also comprises zinc borateparticulates. Preferably, at least some of the sparingly soluble coppersalt-based particulates comprise copper borate. It is known to use a twostage process where a zinc or copper salt is injected into the woodfollowed by a second step, wherein the borax is injected and theinsoluble metal borate is formed in situ. Such a complicated,time-consuming, and therefore expensive process in not sufficientlycost-effective. As the solubility of copper borate is very pH sensitive,in a preferred embodiment the sparingly soluble copper salts comprise analkaline material, e.g., copper hydroxide or copper carbonate, to reducethe solubility of the copper borate. The zinc borate loading can rangefrom 0.025% to 0.5%, for example, independent of the copper loading inthe wood.

In any of the above-described embodiments, the substantially crystallinecopper composition in copper-based particulates and/or copper-basedparticulate material can further comprise one or more solublesubstantially crystalline copper salts, for example copper sulfate,copper fluoroborate; copper fluoride, or mixtures thereof, where thesoluble substantially crystalline copper salts phase is stabilizedagainst dissolution.

In any of the above-described embodiments, the substantially crystallinecopper composition in copper-based particulates and/or copper-basedparticulate material can further comprise the substantially insolublecopper salt copper phosphate, Cu₃(PO₄)₂. In any of the above-describedembodiments, the copper composition in copper-based particulates and/orcopper-based particulate material can further comprise the insolublecopper salt copper 8-quinolinolate. In any of the above-describedembodiments, the composition can further comprise copper quinaldate,copper oxime, or both in particulate form. If there are copper-basedparticulates substantially comprising Cu₃(PO₄)₂ and/or copper oxideand/or copper 8-quinolinolate, the particulates should be exceedinglysmall, e.g., less than about 0.07 microns, preferably less than about0.05 microns, to provide maximum surface area to help dissolution of theparticles, and the wood treatment should contain another type ofsubstantially crystalline (or amorphous sparingly soluble) copper-basedparticulates, e.g., basic copper carbonate, basic copper borate,tribasic copper sulfate, copper hydroxides, and the like.

The zinc analogs of the above are useful for the zinc-based particulatesof the alternate embodiments of the invention. In one embodiment thecopper-based particulate material can further comprise one or more ofcrystalline zinc salts selected from zinc hydroxide; zinc oxides; zinccarbonate; zinc oxychloride; zinc fluoroborate; zinc borate, zincfluoride, or mixture thereof. The zinc salts may be in a separate saltphase, or may be mixed Cu/Zn salts, or combinations thereof. Inpreferred embodiments the particle comprises at least about 40%,preferably at least about 60%, and more preferably at least about 80% byweight of one or more substantially crystalline (or amorphous sparinglysoluble) copper salts, crystalline zinc salts, or mixtures orcombinations thereof.

In one embodiment the copper-based particulate preservative treatmentfor wood can further comprise zinc-based particulates comprising one ormore of crystalline zinc salts selected from zinc hydroxide; zincoxides; zinc carbonate; zinc oxychloride; zinc fluoroborate; zincborate, zinc fluoride, or mixture thereof. The preferred zinc-basedsubstantially crystalline material are zinc hydroxide, zinc borate, zinccarbonate, or mixture thereof, which may be doped with other cations,e.g., from 0.1 to 10% copper, from 0.1 to 10% magnesium, or both, forexample, based on the total weight of the cations in the substantiallycrystalline (or amorphous sparingly soluble) material. In preferredembodiments, the particle comprises at least about 40%, preferably atleast about 60%, and more preferably at least about 80% by weight of oneor more crystalline zinc salts.

Preferred embodiments of the invention comprise particles comprising oneor more of copper hydroxide, alkaline copper carbonate, alkaline copperoxychloride, tribasic copper sulfate, copper borate, or mixturesthereof. The most preferred embodiments of the invention compriseparticles comprising copper hydroxide, alkaline copper carbonate, copperborate, alkaline copper borate, or mixtures thereof.

In preferred embodiments of this invention the slurry comprises: aliquid carrier; sparingly soluble (and preferably substantiallycrystalline) copper based particulates, sparingly soluble (andpreferably substantially crystalline) zinc-based particulates, sparinglysoluble (and preferably substantially crystalline) tin-basedparticulates, or mixtures thereof; and optionally the slurry alsoadvantageously contains one or more organic biocides, one or morecorrosion inhibiting agents, and optionally other ingredients includingthose discussed herein. The particulates, and the sparingly solublesalts forming the core thereof, have been previously discussed. Theorganic biocides can be in the form of a solution with the carrier (forwater soluble biocides); an emulsion; a coating on the sparingly solublecopper based, zinc-based, and/or tin-based particulates; a coating onand/or in other injectable solid particulates; or any combinationthereof. In one embodiment substantially all (e.g., greater than 99% byweight) of the copper-based, zinc-based particulates, and/or tin-basedparticulates of preferred preservatives have a diameter smaller than 0.4microns (400 nanometers). Such particles may be insufficiently large toscatter enough light to discolor wood or wood products treated with theparticles. In another embodiment, exemplary wood preservatives comprisecopper-based particles having a size distribution in which at least 50%of particles have a diameter smaller than about 0.5 .mu.m, 0.25 .mu.m,0.2 .mu.m, or 0.15 .mu.m.

An exemplary preservative of the invention comprises sparingly solublecopper salt (e.g., copper hydroxide) or sparingly soluble zinc saltparticles having an average particle diameter of less than about 500nanometers, for example less than about 250 nanometers, or less thanabout 200 nanometers. In a preferred embodiment, the average particlediameter is at least 25 nanometers, for example, at least 50 nanometers.In a most preferred embodiment, the sparingly soluble (and preferablysubstantially crystalline) copper based particulates, sparingly soluble(and preferably substantially crystalline) zinc-based particulates,and/or sparingly soluble (and preferably substantially crystalline)tin-based particulates advantageously have a median particle size belowabout 0.6 microns, preferably between about 0.1 and about 0.4 microns.The particle size distribution of the particulates is such that lessthan about 1% by weight, preferably less than about 0.5% by weight, ofthe particulates have an average diameter greater than 1 micron.Preferably, the particle size distribution of the particulates is suchthat less than about 1% by weight, preferably less than about 0.5% byweight, of the particulates have an average diameter greater than about0.6 microns. In one embodiment the particle size distribution of theparticulates is such that at least about 30% by weight of theparticulates have an average diameter between about 0.07 microns andabout 0.5 microns. In a preferred embodiment, the particle sizedistribution of the particulates is such that at least about 50% byweight of the particulates have an average diameter between about 0.1microns and about 0.4 microns.

In preferred embodiments of this invention, the slurry is substantiallyfree of alkanolamines, e.g., the slurry comprises less than 1%alkanolamines, preferably less than 0.1% alkanolamines, or is totallyfree of alkanolamines.

In preferred embodiments of this invention, the slurry is substantiallyfree of amines, e.g., the slurry comprises less than 1% amines,preferably less than 0.1% amines, or is totally free of amines, with theproviso that amines whose primary function is as an organic biocide areexcluded.

In preferred embodiments of this invention, the slurry is substantiallyfree of ammonium compounds (e.g., ammonium hydroxide), e.g., the slurrycomprises less than 1% ammonia, preferably less than 0.1% ammonia, or istotally free of ammonium compounds, with the proviso that ammoniumcompounds whose primary function is as an organic biocide are excluded.In another embodiment, the composition comprises an amount of ammoniumhydroxide to keep the pH of the liquid carrier between about 7 and about10, for example between about 7.5 and 9, or between about 8 and about8.5.

In preferred embodiments of this invention, the slurry is substantiallyfree of solvents, e.g., the slurry comprises less than 1% organicsolvents, preferably less than 0.1% organic solvents, or is totally freeof organic solvents.

The slurry contains sparingly soluble (and preferably substantiallycrystalline) copper based particulates, sparingly soluble (andpreferably substantially crystalline) zinc-based particulates, sparinglysoluble (and preferably substantially crystalline) tin-basedparticulates, or mixtures thereof. The sparingly soluble materials mayhave a fraction of additional cations, e.g., zinc and/or magnesium. Theparticulates may have an organic coating covering at least a portion ofthe exterior of at least a fraction of the particulates. For example,the particles can be wetted with an oil or solvent comprising e.g.,linseed oil, turpentine, and/or pine oil, and typically the oil orsolvent will include at least a portion of the organic biocides. Inanother embodiment, the slurry will alternately or additionally compriseinert metal oxide carrier particulates having organic biocide associatedtherewith. The particulates may have an inorganic coating covering atleast a portion of the exterior of at least a fraction of theparticulates. The inorganic coating in one preferred embodimentcomprises copper phosphate formed by having phosphate absorb onto thesparingly soluble copper salt.

The loading of the particulates in the slurry will depend on a varietyof factors, including the desired copper loading in the wood, theporosity of the wood, and the dryness of the wood. Calculating theamount of copper-based particulates and/or other particulates in theslurry is well within the skill of one of ordinary skill in the art.Generally, the desired copper loading into wood is between 0.025 andabout 0.5 pounds copper per cubic foot of wood.

In a preferred embodiment, the liquid carrier consists essentially ofwater and, optionally, one or more additives to aid particulatedispersion, pH maintenance, interfacial tension (surfactants), andanticoagulants. In another embodiment, the carrier consists essentiallyof water and, optionally, one or more additives to aid particulatedispersion, pH maintenance, interfacial tension (surfactants),anticoagulants, and oil-in-water emulsion of oil containing organicbiocides dissolved therein.

Advantageously, the pH of the liquid carrier is between about 7 andabout 9, for example, between about 7.5 to about 8.5. The pH can beadjusted with sodium hydroxide, potassium hydroxide, alkaline earthoxides, methoxides, or hydroxides; or less preferably ammoniumhydroxide. The pH of the injectable slurry is typically between pH 6 and11, preferably between 7 and 10, for example, between 7.5 and about 9.5.Acidic pH slurries are not preferred because several of the sparinglysoluble copper salts of this invention have a higher solubility at lowerpH. Therefore, delays in preparing the slurry, injecting the slurry, andremoving the water carrier may result in undesired dissolution ofsparingly soluble material from the particulates. The pH can be adjustedto the desired pH with alkali or alkaline earth oxides, methoxides, orhydroxides, or less preferably ammonium hydroxide. Alkaline earth basesare less preferred because if carbon dioxide or carbonates are presentin solution, there is a possibility of precipitation, for example, ofcalcite. Such precipitation may create undesired plugging of the woodduring injection. The preferred ingredients to increase the pH is analkali hydroxide, e.g., sodium hydroxide or potassium hydroxide. The pHmodifying agent may be provided in the form of a preferably aqueoussolution comprising at least one hydroxide salt.

The slurry is beneficially buffered, by, for example, adding phosphoricacid or salts thereof in an amount sufficient to give a phosphatecontent of between about 5 ppm and about 500 ppm. An alternative buffercomprises an alkali bicarbonate and alkali carbonate. The higherconcentrations of phosphates may be beneficial if the particulates donot have any coatings formed thereon, as the soluble phosphate ions willdiscourage dissolution of the copper salts from the particulates intothe liquid carrier. The salts of metal phosphates are extremelyinsoluble, for example, the solubility product constant of copperphosphate is about 1 E-37, so in pure water this amount of phosphatewould limit the copper ion concentration to a negligible quantity. Thephosphate ions would therefore discourage dissolution andre-precipitation of the copper, zinc, tin, or any combination thereof.This phosphate may also allow an existing phosphate-based coating torepair after damage by for example abrasion with other particles orabrasion while being handled. Finally, the presence of phosphate ionswill slow the leach rate of copper from the wood. On the other hand, thebioactive efficacy of copper phosphate is probably very low, for thesame reasons that the efficacy of copper oxides is low. The solubilizedcopper ions are believed to be bioactive and therefore contribute to thebioactivity of the formulation, and the solubility of copper phosphateis very low. Therefore, it is desirable that any copper phosphatecoating on the particulates be so thin as to be short-lived in the wood.Excessive soluble phosphate may not allow the phosphate coating toreadily break down in the wood, and this could impair the bioactivity ofthe particulates. Also, if the mixing tank has, for example, a residualsalts from previous injection of soluble materials, then the phosphatescan result in unwanted precipitates forming. For this reason theconcentration of phosphates in the liquid carrier is beneficially keptbelow 1000 ppm, for example below 500 ppm or below 100 ppm.

In one embodiment the slurry comprises between 50 and 800 ppm of one ormore scale precipitation inhibitors, particularly organophosphonates.Alternately or additionally the slurry may contain between about 50 andabout 2000 ppm of one or more chelators. Both of these additives aremeant to inhibit precipitation of salts such as calcium carbonate andthe like, where the source of calcium may be from the water used to makeup the slurry. The preferred inhibitors are hydroxyethylidenediphosphonic acid (HEDP), diethylenetriaminepentamethylenephosphonicacid (DTPMP), and/or 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC).If the preservative is in a slurry concentrate, the slurry shouldcomprise between 10 mmoles and 100 mmoles/L of HEDP, or between 30mmoles and 170 mmoles/L of PBTC or DTPMP. Mixtures of inhibitors arepreferred, as concentrates may have more inhibitor than can readily besolubilized therein. If the preservative is in a solid form, thepreservative should comprise between about 0.1 to about 1 mole HEDP perkg of particulates, or between about 0.17 to about 2 mole PBTe and/orDTPMP per kg of particulates.

In one embodiment of the invention, a precipitate comprisingcopper-based particles is prepared in the presence of a material thatinhibits precipitation of at least one of calcium and magnesium.Alternatively, a material that inhibits precipitation of at least one ofcalcium and magnesium is added to a mixture comprising copper-basedparticles of the invention. In one embodiment, the precipitationinhibitor is a chelator comprising having at least one ethylene diaminecompound, such as an ethylenediamine-tetramethylene compound orethylenediaminetetracetate compound. An acid, such as a phosphonic oracetic acid, of the ethylenediamine compound may be used. Salts of theethylenediamine compound may also be used. In one embodiment, theprecipitation inhibitor comprises at least one and preferably at leasttwo phosphonic groups. The precipitation inhibitor may comprise aphosphonic acid or salt of a phosphonic acid. The precipitationinhibitor may comprise at least one of a hydroxyethylidene diphosphonicacid and an aceto diphosphonic acid. A suitable phosphonate may besynthesized from phosphorous acid by reaction with formaldehyde andeither ammonia or amines. A wood preservative of the invention mayinclude at least one of a ethylenediamine tetra methylenephosphonicacid, a hexamethylenediamine tetra methylenephosphonic acid, adiethylenetriamine penta methylenephosphonic acid, and a 1-hydroxyethane diphosphonic acid.

In some embodiments of the invention, the sparingly soluble (andpreferably substantially crystalline) copper based particulates,sparingly soluble (and preferably substantially crystalline) zinc-basedparticulates, sparingly soluble (and preferably substantiallycrystalline) tin-based particulates, or mixtures thereof, are used inconjunction with a liquid carrier comprising soluble copper, forexample, any of the soluble copper formulations discussed in thebackground, including, for example, a copper monoethanolamine carbonatecomplex, copper monoethanolamine borate complex, copper azole borate, orcopper citrate. Advantageously, this soluble copper material is keptseparate from the particulate slurry or paste of this invention untilthe injectable slurry is formulated. If such material is admixed into aconcentrated slurry or paste for shipping and storage, then beneficiallythe particulates have one or more protective coating layers thereon tominimize copper dissolution of the particulates.

In some embodiments of the invention, the sparingly soluble (andpreferably substantially crystalline) copper based particulates,sparingly soluble (and preferably substantially crystalline) zinc-basedparticulates, sparingly soluble (and preferably substantiallycrystalline) tin-based particulates, or mixtures thereof, are used inconjunction with a liquid carrier comprising one or more soluble boratesalts. Soluble borates can be added in an amount from about 5 ppm toabout 2000 ppm in the slurry, where less than 5 ppm has little effectand more than 2000 ppm is cost-prohibitive. Borates have both a biocidalactivity and a fire retardant activity.

In some embodiments of the invention, the sparingly soluble (andpreferably substantially crystalline) copper based particulates,sparingly soluble (and preferably substantially crystalline) zinc-basedparticulates, sparingly soluble (and preferably substantiallycrystalline) tin-based particulates, or mixtures thereof, are used inconjunction with a liquid carrier comprising one or more solublechromate salts. Soluble chromates can be added in an amount from about 5ppm to about 2000 ppm in the slurry, where less than 5 ppm has littleeffect and more than 2000 ppm is cost-prohibitive. Chromates have both abiocidal activity and may have a corrosion-reducing activity.

Increased corrosion of metal fillings has been observed in formulationsusing soluble copper preservatives, as opposed to the prior art CCAformulations. The slurry, having a slightly basic pH and having very lowamine content, is expected to reduce the corrosion rate over that seenwith soluble copper. There are additional treatment that can help reducecorrosion. The presence of small quantities of buffered phosphate mayfurther reduce corrosion. Eliminating certain sparingly soluble saltssuch as the oxychlorides will remove chloride, which will reducecorrosion from that source. Finally, some of the injectable particulatescan comprise at least a portion of reduced metallic zinc or copper. Theparticulates are advantageously sized about the same as for theinjectable particulates comprising the sparingly soluble, usuallysubstantially crystalline copper salts. Indeed, in addition to beinguseful in slurries of this invention, corrosion of metallic fittings maybe somewhat alleviated by incorporating metallic copper and/or zincparticulates in the soluble copper solution preservatives of the priorart. Metallic zinc and copper are not considered to be substantiallycrystalline, nor are they considered to be sparingly soluble salts. Theamount of these anti-corrosion metallic particulates can range fromabout 1 part to about 25 parts per 100 parts of copper in the sparinglysoluble copper salts.

Contact with air can facilitate oxidation of certain sparingly solublecopper salts, for example, copper hydroxide (especially in very smallparticulate form, and especially if not coated and/or if not containinga stabilizer such as magnesium ions, to form into copper oxides). Thistransition is generally not preferred because copper oxide has suchlimited solubility that it may not be sufficiently bioactive. Theconcentrated slurry or paste may comprise one or more antioxidants.Soluble sulfite salts between 5 ppm and 100 ppm in the liquid carrier isa useful inexpensive antioxidant.

If the wood preservative treatment will comprise organic biocides, thesebiocides may be partially or fully coated onto the sparingly soluble(and preferably substantially crystalline) copper based particulates,sparingly soluble (and preferably substantially crystalline) zinc-basedparticulates, sparingly soluble (and preferably substantiallycrystalline) tin-based particulates, or mixtures thereof. Preferredpreservative materials inhibit organisms that may be resistant tocopper-based preservatives. Moldicides useful in wood or wood productpreservation are also preferred organic biocides. Alternatively oradditionally, these biocides may be partially or fully coated onto theavailable surface area of an inert particulate carrier. If the biocidesare to be added to the slurries as an emulsion, the organic biocides arebeneficially kept separate from the concentrated slurry or paste of thisinvention until the injectable slurry is formulated.

The slurry can advantageously contain one or more additives to aidwetting, for example surfactants. Surfactants may be in solution, oralternatively may bind to the surface. When bound to the surface thesesurfactants function as disbursing agents. A dispersing agent may becombined with the precipitated copper-based particles. Alternatively,copper-based particles may be formed in the presence of the dispersingagent. Preferred dispersing agents include a surface active portion thatinteracts with the copper-based particle and a second preferablydifferent portion, which operates to inhibit irreversible agglomerationof the copper based particles. For example, a polyacrylate dispersingagent may include at least one carboxyl group capable of associating,such as electrostatically, with a copper-based particle and a second,hydrophobic portion that may operate to inhibit the permanentagglomeration of the copper based particles. Exemplary dispersing agentsmay include at least one of a surfactant, a polyacrylate, apolysaccharide, a polyaspartic acid, a polysiloxane, and a zwitterioniccompound. Exemplary compounds useful as dispersing agents are disclosedin for example, Kirk-Othmer, Encyclopedia of Chemical Technology, 3rdEdition, Vol. 22 (John Wiley & Sons, 1983); Napper, PolymericStabilization of Colloidal Dispersion (Academic Press, 1983); and Rosen,Surfactants & Interfacial Phenomena, 2nd edition (John Wiley & Sons,1989), all of which are incorporated herein by reference. In oneembodiment of the invention, the copper-based particles may comprise apolymer. In this embodiment, the ratio of the weight of copper presentin the particles to polymer present in the particles may be at leastabout 1 to 1, for example at least about 2 to 1, 4 to 1, 5 to 1, 7 to 1,or at least about 10 to 1. For example, if ratio of the weight of copperpresent in the particles to the weight of polymer present in theparticles is at least about 2 to I, the particles comprise at leastabout twice as much copper by weight as polymer. Another aspect of theinvention relates to a preservative useful for wood or wood products,the preservative preferably comprising a preferably aqueous suspensionof copper based particles. If a dispersing agent is present in thesuspension, the ratio of the weight of copper present in thecopper-based particles of the suspension to the weight of dispersingagent present in the suspension may be at least about 1 to 1, forexample at least about 5 to 1, 10 to 1, 15 to 1, 20 to 1 or at leastabout 30 to 1.

In one embodiment, the dispersing agent is substantially free ofphosphate ion. For example, the dispersing agent may be substantiallyfree of trisodium phosphate. The dispersing agent may be substantiallyfree of silicates, sodium carbonate and ammonia. By substantially freeof one or more particular dispersing agents, it is meant that the weightpercent of the one or more dispersing agent relative to the copper-basedparticles is less than 3%. In one embodiment, the weight percent of theone or more particular dispersing agents relative to the copper-basedparticles is less than about 2%, such as less than about 1%, forexample, less than about 0.5%. In one embodiment, the dispersing agentis free of at least one of phosphate ion, trisodium phosphate,silicates, sodium carbonate, and ammonia.

Dispersing agents aid particulate dispersion and to prevent aggregationof particulates. Sub-micron sized particulates have a tendency to formmuch larger aggregates. Aggregates as used herein are physicalcombinations of a plurality of similarly-sized particles, often broughttogether by VanDerWaal's forces or electrostatic forces. Bysimilarly-sized we mean the particles forming the aggregate havediameters that are generally within a factor of five of each other. Suchaggregates are not desired in the compositions of this invention. Ifaggregates are allowed to form, they often can age into a stableaggregate that can not be readily broken up by mechanical agitation, forexample by vigorous stirring of a slurry. Such aggregates may grow to asize where the aggregates are not readily injectable, or may be of asize to make the aggregates visible, therefor giving undesired color. Inpreferred embodiments of the invention at least 30%, preferably at least60%, more preferably at least 90% by weight of the substantiallycrystalline copper-based particulates in a slurry are mono-disbursed,e.g., are not in aggregates. To prevent particulates from agglomerating,the concentrated slurry or paste may comprise cationic, anionic, and/ornon-ionic surfactants; emulsifiers such as gelatine, casein, gum arabic,lysalbinic acid, and starch; and/or polymers, such as polyvinylalcohols, polyvinyl pyrrolidones, polyalkylene glycols andpolyacrylates, in quantities of 0.1 to 20% by weight, based on theweight of the particulates.

Another aspect of the invention relates to a preservative useful forwood or wood products, the preservative preferably comprising apreferably aqueous suspension of copper based particles. The suspensionmay be stabilized by a suspension-stabilizing amount of a dispersingagent. Preferred dispersing agents include a surface active portion thatinteracts with the copper-based particle and a second, preferablydifferent portion, which operates to inhibit irreversible agglomerationof the copper-based particles. For example, a polyacrylate dispersingagent may include at least one carboxyl group capable of associating,such as electrostatically, with a copper-based particle and a second,hydrophobic portion that may operate to inhibit the permanentagglomeration of the copper-based particles. Exemplary dispersing agentsmay include at least one of a surfactant, a polyacrylate, apolysaccharide, a polyaspartic acid, a polysiloxane, or a zwitterioniccompound. If a dispersing agent is present in the suspension, the ratioof the weight of copper present in the copper-based particles of thesuspension to the weight of dispersing agent present in the suspensionmay be at least about 1 to 1, for example at least about 5 to 1, 10 to1, 15 to 1, 20 to 1 or at least about 30 to 1.

The slurry formulations mentioned can be prepared in a manner known perse, for example by mixing the active compounds with the liquid carrier,and including emulsifier, dispersants and/or binders or fixative, andother processing auxiliaries. Particulates can be provided in aconcentrated slurry, in a very concentrated paste, as dry particulates,as coated dry particulates, as part of a dry pre-mix, or any combinationthereof.

Slurry Concentrate—If the wood preservative is to be manufactured,stored, or transported in a wetted form, it is beneficial that it be ina concentrated form to minimize the volume and increased handlingexpense. Preferably the concentrated slurry or paste comprises between5% and 80% by weight, for example between about 15% and 40%, ofsparingly soluble (and preferably substantially crystalline) copperbased particulates, sparingly soluble (and preferably substantiallycrystalline) zinc-based particulates, sparingly soluble (and preferablysubstantially crystalline) tin-based particulates, or mixtures thereof,with the remainder of the concentrated slurry or paste being a fluidcarrier. The concentrated slurry or paste may further comprise solidparticulates that are carriers for one or more organic biocides, solidparticulates comprising metallic copper and/or zinc as corrosioninhibitors, or both. The fluid carrier beneficially comprises one ormore additives as discussed for the slurry, including anti-oxidants;surfactants; disbursing agents; other biocidal salts and compounds;chelators; corrosion inhibitors, e.g., phosphates or metallic zinc orcopper particulates; pH modifiers and/or buffers; and the like. Theconcentration of these additives will depend in part on the degree towhich the slurry concentrate is expected to be diluted to make acommercially useful injectable slurry having the proper copper loading.

The moisture content of the copper-based particles of the invention maybe reduced, such as by drying. A dispersing agent may be used to inhibitirreversible agglomeration of reduced moisture particles of theinvention. The reduced moisture particles may be diluted, such as byhydration with water or combination with another liquid. Generally,dilution is with water, beneficially fresh water.

Another aspect of the invention relates to an agglomeration comprising aplurality of copper-based particles and, optionally, a dispersing agent.The agglomeration may also include one or more materials in addition tothe copper-based particles that also provide a wood or wood productpreservative function. The agglomeration may have a liquid content(excluding any additional preservative material that may be present) ofless than about 75% by weight, for example, of less than about 50%, lessthan about 25%, less than about 15%, or less than about 5% by weight.The liquid may be water. The agglomeration may be diluted and/ordispersed with mixing or agitation, such as mechanically orultrasonically.

As in the injectable slurry itself, the particle size distribution ofthe particulates is such that less than about 1% by weight, preferablyless than about 0.5% by weight, of the particulates have an averagediameter greater than 1 micron. Preferably the particle sizedistribution of the particulates is such that less than about 1% byweight, preferably less than about 0.5% by weight, of the particulateshave an average diameter greater than about 0.6 microns. The particlesize distribution of the particulates is such that at least about 30% byweight of the particulates have an average diameter between about 0.07microns and about 0.5 microns. In a preferred embodiment, the particlesize distribution of the particulates is such that at least about 50% byweight of the particulates have an average diameter between about 0.1microns and about 0.4 microns.

The pH of the wood preservative in the form of a concentrate or paste isin general between pH about 6 and about 13, preferably between about 7and about 10.5, for example, between about 7.5 and about 9.5. The pH canbe adjusted to the desired pH with alkali or alkaline earth oxides,methoxides, or hydroxides; or less preferably ammonium hydroxide. Thepreferred ingredient to increase the pH is an alkali hydroxide such assodium hydroxide. The concentrated slurry or paste is beneficiallybuffered, for example, by adding phosphoric acid in an amount sufficientto give a phosphate content of between about 10 ppm and about 1000 ppm.

If the wood preservative comprises organic biocides, these biocides maybe partially or fully coated onto the sparingly soluble (and preferablysubstantially crystalline) copper based particulates, sparingly soluble(and preferably substantially crystalline) zinc-based particulates,sparingly soluble (and preferably substantially crystalline) tin-basedparticulates, or mixtures thereof. Alternatively, or additionally, theseorganic biocides may be partially or fully coated onto the surface areaof an inert particulate carrier. If the organic biocides are to be addedto the slurries as an emulsion, the organic biocides are beneficiallykept separate from the concentrated slurry or paste of this inventionuntil the injectable slurry is formulated.

Dry Particulates and Dry Mix For Slurry—The particulates are preferablysold as a dry component. The dry component can be simply thecopper-based, zinc-based, and/or tin based particulates, which may becoated or uncoated. If coated, the coating can be inorganic, organic, orboth. The particulates advantageously comprise one or more additivessuch as are described as being present in the slurry, including, forexample, inert particulates having organic biocides thereon;anti-oxidants; surfactants; disbursing agents; other biocidal salts andcompounds; chelators; corrosion inhibitors, e.g., phosphates or metalliczinc or copper particulates; pH modifiers; and/or buffers, such ascarboxylic acid salts, or inorganic salts, such as phosphate salts andthe like. The additives can be coated onto the sparingly soluble copperbased particulates and/or can be a second particulate.

The dry-mix material advantageously has, in addition to dry particulatesdiscussed above, all necessary components in a single mix, and eachcomponent is present in a range that is useful when the dry mix isformed into an injectable slurry. The dry-mix material may optionally,but preferably, incorporate a granulating material, which is a materialthat, when wet, holds a plurality of particulates together in the formof a granule, but that dissolves and releases the individualparticulates on being admixed with the liquid carrier. Granules arepreferred over sub-micron-sized particulates because of dust problemsand also the ease of measuring and handling a granular mixture.Granulating agents can be simple soluble salts, for example alkalicarbonates, that are sprayed onto or otherwise admixed with theparticulate material. Several additives to a slurry can be also used asgranulating agents.

One embodiment of the invention relates to a dry-mix material having acopper content of at least about 8% by weight. A preferred materialincludes a plurality of copper-based particles, which may be in the formof granules. The material may be shipped, such as in granular form, to alocation where the material will be prepared for use as a woodpreservative. The dry-mix material may also comprise at least one of awetting agent; a dispersing agent; a diluent, which may be a particulatecomprising organic biocides thereon; an antifoaming agent; and anadditional material having a biocide function.

One embodiment of the invention relates to a dry-mix material having acopper content of at least about 15% by weight. A preferred dry-mixmaterial includes a plurality of copper based particles, which may be inthe form of granules. The dry-mix material also comprises at least oneof a wetting agent, a dispersing agent, a diluent, an antifoaming agent,or an additional material having a biocide function. In one embodiment,the dry-mix material is a granular material comprising about 50% toabout 70%, for example about 58%, copper hydroxide or other sparinglysoluble copper salts, about 10% to about 25%, for example about 18%, ofa dispersing agent, such as Borresperse NA, about 1% to about 8%, e.g.,about 4%, of a wetting agent, such as Morwet EP, and about 10% to about30% filler, e.g., about 20% attapulgite clay, such as Diluex A.

In one embodiment, the dry-mix material is a granular materialcomprising about 40% to about 80% by weight of a sparingly solublecopper salt, e.g., copper hydroxide, about 5% to about 30% of adispersing agent, such as Borresperse NA, about 1% to about 10% of awetting agent, such as Morwet EP, and about 5% to about 30% of a inertparticulate filler which may additionally comprise organic biocidesabsorbed thereon, e.g., attapulgite clay, such as Diluex A. In oneembodiment, the dry-mix material is a granular material comprising about58% copper hydroxide, about 18% of a dispersing agent, such asBorresperse NA, about 4% of a wetting agent, such as Morwet EP, andabout 20% attapulgite clay, such as Diluex A.

Another aspect of the invention relates to dry-mix material comprising acopper content of at least about 15%, for example, at least about 20%,such as at least about 30% by weight. In one embodiment, the dry-mixmaterial may have a copper content of about 35% by weight. The dry-mixmaterial has a copper content of less than about 50%, for example, lessthan about 45%, such as less than about 40% by weight. The dry-mixmaterial may comprise a plurality of granules each comprising aplurality of copper-based particles. The copper-based particles may beassociated with a dispersing agent.

In one embodiment, the dry-mix material comprises A) about 30% to about70% by weight of a slightly soluble copper salt, e.g., copper hydroxide,for example, about 35% to about 65%, such as about 38% to about 61% ofthe slightly soluble copper salt; B) about 10% to about 35% by weight,such as about 15% to about 30% of at least one dispersing agent, e.g.,lignosulfonates or polyacrylates; C) about 2.5% to about 20% by weight,such as about 5% to about 15% of at least one wetting agent, forexample, a surfactant, e.g., Morwet EP available from Barton Solvents,Inc.; D) about 5% to about 25% by weight, such as about 10% to about 20%of at least one diluent, for example soluble and insoluble diluents,such as those used in agricultural products, e.g., clay, such as anattapulgite clay, or particulate carrier particles comprising organicbiocide; E) about 0.05% to about 7.5% by weight, such as about 0.1% toabout 5%, of at least one antifoam agent; and optionally F) about 2.5%to about 25%, alternatively less than about 7.5%, such as less thanabout 5% by weight, of water.

The dry-mix material may be shipped in granular form. The dry-mixmaterial of the invention offers reduced shipping costs and improvedease of handling compared to known preservative materials. A user mayreceive the dry-mix material as a flowable material comprising aplurality of copper-based particles. The dry-mix material may bediluted, for example, with water or another liquid. The copper-basedparticles of the dry-mix material may be injected into wood and/or woodmaterials as a preservative. Mechanical agitation and/or mixing may beused to disperse the granules in the liquid. Upon dispersing thematerial, wood or wood products may be treated with the dispersedmaterial, such as by subjecting the wood or wood products to vacuum andor pressure in the presence of the dispersed material. Upon dispersinggranules of the material, dispersed copper-based particles preferablyremain suspended for at least about 30 minutes without furtheragitation, preferably, even in standard hard water having a hardness ofabout 342 ppm. Once dispersed, about fifty percent of the dispersedcopper-based particles may have diameters less than about 1 micron, forexample, less than about 0.5 micron, such as less than about 0.25micron. In one embodiment, about 50% of the dispersed copper-basedparticles have diameters less than about 0.2 micron, for example, about50% of the dispersed copper-based particles have diameters of about 0.1micron.

The copper-based material may comprise additional material providing awood preservative and/or biocide function. For example, in oneembodiment, the additional material comprises a plurality ofcopper-based particles and a co-biocide. Exemplary co-biocides mayinclude, for example, one or more of a triazole compound, a quaternaryamine, and a nitrosoamine.

Leaching Data

One object of the invention is to provide an effective, injectablecopper-based particulate preservative treatment that has leachingcharacteristics similar to CCA. It is known that copper arsenate(Cu₃(AsO₄)₂) injected as a molecular layer is effective as apreservative. Therefore, the particulate preservative should provide acopper concentration roughly similar (for example, about the same towithin a factor of three times) to that provided by copper arsenatetreatment. Generally, leach rate tests involve high-leaching medium flowrates so the leaching medium can not easily dissolve the sparinglysoluble salts, and therefore measured leach rates of particulates areexpected to be low compared to leach rates from more soluble salts. By“leach rate similar to CCA,” we mean the leach rate using the AWPAStandard Method E11-97 (1997), determined as percent of copper leachedper hour. For a particulate inhibitor injected into wood is within afactor of about 2 above, preferably within a factor of about 1.5 above,to within a factor of 5 below, preferably within a factor of about 3below, more preferably within a factor of about 2 below, the percent ofcopper leached from CCA-treated wood at 240 hours using the AWPAStandard Method E11-97 (1997), by using a test extending to at least 300hours duration. Another object of the invention is to provide aneffective, injectable copper-based particulate preservative treatmentthat retains more than 94% of the injected copper in a 14 day standardleach test.

Advantageously the copper-based particulate is an effectivepreservative. To be effective, the copper-based particles comprise oneor more sparingly soluble copper salts that release a small buteffective concentration of soluble copper when wetted with water. If thecopper salts have too high a solubility, the copper is quickly leachedout of the wood and contaminates the environment rather than protectingthe wood. If the copper salts have too Iowa solubility, the copper salts(and copper oxides) are not bioactive. The dissolution rate/leach rateof the sparingly soluble copper salts used in the particulates will be afunction of 1) the solubility of the sparingly soluble copper salt(s) inthe leaching medium; 2) the surface area of the sparingly soluble coppersalts available to contact the leaching medium; 3) the lattice energy ofthe crystal which must be overcome to dissolve the crystal; and 4) theflow characteristics of the leaching medium in the wood matrix,especially boundary layer effects. Each of these properties plays a rolein every flowrate scenario, but some are more dominant than others atcertain times. We believe the leach rates will be governed primarily bythe solubility of the sparingly soluble salts and by boundary layereffects of the copper and counterions diffusing from the particulates inregimes where the leaching medium is moving extremely slowly, e.g., lessthan a few millimeters per day. At intermediate leachant flow rates, webelieve the leach rate of copper will depend primarily on the availablesurface area. At higher rates, such as found in the standard testmethods typically used by industry, the leach rates will be governedmore by the available surface area of the sparingly soluble salts and bythe lattice energy of the crystal.

Generally, surface area is known be an important factor. This isbecause, as the sparingly copper salts exist as approximate pointsources within the wood matrix, the leaching medium typically does notcontact a sufficient amount of particulates for a sufficient time tobecome saturated with the sparingly soluble copper salts. Dissolution isa function not only of the pH of the water within the wood and thesolubility product of the particular salts in water, but also of dynamicconditions. Since the copper is present in the wood as particulates,dissolution of copper will also be restricted by the low surface area ofthe particles. Larger particulates will reduce the leaching rate in mostleaching regimes. The dissolution of larger particulates is moredependent on surface effects than is the dissolution of smallerparticulates, in part because the available surface area is lower forlarger particulates. At low flow rates, boundary layer effects maymultiply the effects of lower surface area, but at typical leachingregimes boundary layer effects may be minimized if the flow of theleaching medium through the wood matrix is turbulent.

The easiest way to alter surface area is to change particle size. In asimplistic model, reducing the average particle size by one half willincrease the available surface area by about a factor of 2. If theparticulates become too small, e.g., below about 0.02 microns (20nanometers) in diameter or below about 10 nanometers in diameter, formany of the sparingly soluble copper salts, we believe the leachingmedium will always approximate being saturated by the sparingly solublecopper salts and the available surface area will approach that of amonolayer, giving leaching properties of an injected soluble copper. Thecrystals may then dissolve too quickly if subjected to a high leachingregime for an extended period of time. Further, we believe that highleachant flow rates may dislodge and remove from the wood matrix verysmall particulates. For this reason in preferred embodiments of theinvention at least about 30% or more of the sparingly soluble salts arepresent as particulates having a diameter greater than about 0.1microns.

Generally, the available surface area can be further reduced by thepresence of one or more coatings, be they organic, inorganic, or both.The coatings must be designed to have a coverage and efficiency suchthat at least a bioactive amount of copper is leached from the sparinglysoluble copper salts in the particulates. In some embodiments, thecoating is dissolved over a period of time, thereby allowing theavailable surface area of the sparingly soluble copper salts to increasewith time. This is advantageous because newly-installed wood generallydoes not need biocides to be released until the bio-organisms invade orcontact the wood, and this usually takes some time.

The solubility of the sparingly soluble copper salts can be estimatedbased on values of the solubility product constant. However, thepresence of ions such as phosphate in the wood matrix will reducesolubility, while the presence of acids in the leachant will greatlyincrease solubility of most of the preferred sparingly soluble salts. Atlow flow rates, the pH of the leaching medium will be modified by thedissolution of the copper hydroxides and the copper carbonates. Theisoelectric point of copper hydroxide is at about pH 11, making copperhydroxide a very effective base. The presence of other salts, forexample phosphate ions, can further hinder leach rates by temporarilyholding the solubilized copper, reducing the flow rate of copper throughthe wood matrix. At high leaching medium flow rates, however, such asare used in standard leaching tests, the flow rates are such that thepresence of hydroxides, phosphates, and the like are minimized.

Generally, the leach rate of copper from particulates of sparinglysoluble copper salts disposed in a wood matrix is dependent on particlesize (and hence particle size distribution), leaching medium flow ratesthrough the wood matrix, and a variety of other factors. The copperbased particulates of the invention advantageously have a low leach rateat both relatively high leaching medium flow rates and at relatively lowleaching medium flow rates, because the copper-based particulateshave 1) a wide distribution of particle sizes, 2) sparingly solublesalts of differing solubilities, or 3) both.

Examples

We have successfully injected slurries comprising sub-micron-sizedparticles of various sparingly soluble copper salts into standard 1 inchcubes of Southern yellow pine. Copper development by calorimetric agents(dithio-oxamide/ammonia) showed the copper to be fully penetrated acrossthe block in the sapwood portion. FIG. 3 shows the penetration ofinjected particulate copper hydroxide developed with dithio-oxamide inthe third picture. The stain corresponds to copper. Subsequent acidleaching and quantitative analysis of the copper from two blocks showedthat loadings of 95% and 104% of expectation, or essentially 100%average of expectation had occurred. At 100% loading, values of 0.22 lbsof copper per cubic foot would be obtained.

[Leaching data from wood preserved with a prior art soluble solution ofcopper MEA and from a slurry of injected copper hydroxide particulatesof this invention was measured following the AWPA Standard MethodE11-97. The total copper leached from wood preserved withcopper-MEA-carbonate is 5.7% at 6 hours, 8.5% at 24 hours, 11% at 48hours, 22% at 96 hours, 36% at 144 hours, 49% at 192 hours, 62% at 240hours, 69% at 288 hours, and 76% at 336 hours. The amount of copperleached from copper hydroxide particulates was 0.4% at 6 hours, 0.6% at24 hours, 0.62% at 48 hours, 1.0% at 96 hours, 1.6% at 144 hours, 2.1%at 192 hours, 3.2% at 240 hours, 3.4% at 288 hours, and 3.7% at 336hours.

Leaching data from wood was measured using the AWPA Standard MethodE11-97 for the following preservative treatments, where unless specifiedthe tebuconazole (TEB) concentration was added as an emulsion at 3% ofthe weight of the added copper: A) TEB and injected basic coppercarbonate particulates; B) traditionally CCA-treated wood (as acontrol); C) TEB and copper methanolamine carbonate (as a control,believed to approximate the currently available Wolman E treatment); D)TEB and injected basic copper carbonate particulates with sodiumbicarbonate buffer; E) injected basic copper carbonate particulates; F)TEB and injected copper hydroxide particulates modified with zinc andmagnesium; G) about 5% TEB and injected copper hydroxide particulatesmodified with phosphate coating; and H) TEB and injected tribasic coppersulfate particulates; I) TEB and injected copper oxychlorideparticulates. The leaching data for the various particulate slurries andfrom two controls are shown in FIG. 2.

Using the copper leach rate of CCA as a standard, and viewing the totalleached copper at 96 and 240 hours as representative, the leach rateratios given by the “total leached copper to total CCA-leached copper”is given in Table 3 below:

96 hr. ration 240 hr. ration Ex. Description of Preservative System toCCA to CCA A 3% TEB and basic copper carbonate 0.67:1 0.51:1particulates C 3% TEB and copper MEA carbonate  5.2:1 3.85:1(comparative) D 3% TEB and basic copper carbonate 0.54:1 0.46:1particulates with sodium bicarbonate buffer E basic copper carbonateparticulates 0.77:1 0.63:1 F 3% TEB and copper hydroxide with  0.2:10.19:1 Zn and Mg particulates G 5% TEB and copper hydroxide  1.0:10.88:1 particulates modified with phosphate coating H 3% TEB andtribasic copper sulfate 0.96:1 0.88:1 particulates I 3% TEB and copperoxychloride  1.4:1 1.17:1 particulates

Of the sparingly soluble salts used, the leach rate in descending orderis copper MEA carbonate (comparative)>>copper oxychloride>tribasiccopper sulfate and/or copper hydroxide with phosphate>basic coppercarbonate>copper hydroxide with Zn and Mg. The isoelectric point ofcopper oxychloride is about 5 to 5.5, and the isoelectric point oftribasic copper sulfate is about 6 to 6.5. As these materials are verypoor bases, the higher leach rates. from the materials is consistentwith expected higher solubility at lower pH values.

The presence of TEB reduced leach rates from basic copper carbonate byabout 20%, most likely due to TEB partially coating particulates.

A buffering system, sodium bicarbonate, reduced the leach rates fromTEB/basic copper carbonate by about 10% relative to a preservativewithout the buffer.

Surprisingly, the phosphate material in the copper hydroxide did notappear to show any protective value at all. The reason for this is notclear. Copper hydroxide with magnesium and zinc ions showed the lowestleach rates.

Method of Preserving Wood

Another aspect of the invention relates to wood or a wood productcomprising copper based particles and, optionally, one or moreadditional materials having a preservative function, injected into thewood or wood product. An exemplary piece of wood comprising copper-basedparticles has a volume of at least about 6 cm³, for example, at leastabout 100 cm³, such as at least about 1,000 cm³.

The material of this invention is useful for wood, and also for woodcomposites. Preferred wood composites have the preservative of thisinvention either mixed with the wood particles before bonding, orpreferably injected into the wood particulates and dried prior tobonding. Exemplary wood products include oriented strand board (OSB),particle board (PB), medium density fiberboard (MDF), plywood, laminatedveneer lumber (LVL), laminated strand lumber (LSL), hardboard, and thelike.

In one embodiment, the wood or wood product has a surface, a thickness,a width, and a length. Preferably, the wood or wood product comprises ahomogenous distribution of copper based particles of the invention. Inone embodiment, the volume number density of the copper based particles5 cm from the surface, and preferably throughout the interior of thewood or wood product, is at least about 50%, for example, at least about60%, at least about 70%, or at least about 75% of the volume numberdensity of the copper-based particles about 1 cm from the surface.

Wood or wood products comprising copper-based particles in accordancewith the present invention may be prepared by subjecting the wood tovacuum and/or pressure in the presence of a flowable material comprisingthe copper-based particles. A pre-injection of carbon dioxide followedby vacuum and then injection of the slurry is a preferred method ofinjecting the slurry into wood. Injection of particles into the wood orwood product from a flowable material comprising the particles mayrequire longer pressure treatments than would be required for liquidsfree of such particles. Pressures of, for example, at least about 75psi, 100 psi, or 150 psi may be used. Exemplary flowable materialsinclude liquids comprising copper-based particles, emulsions comprisingcopper-based particles, and slurries comprising copper-based particles.

1-20. (canceled)
 21. A wood preservative composition comprising: aplurality of milled particles comprising a sparingly soluble coppersalt; and one or both of an alkanolamine and ammonia, wherein thecomposition is suspended in an aqueous carrier; and wherein thealkanolamine or ammonia, or both, are each in an amount less than 10% byweight of the composition and the aqueous carrier.
 22. The compositionof claim 21, wherein the alkanolamine or ammonia, or both, are each inan amount less than 5% by weight of the composition and the aqueouscarrier.
 23. The composition of claim 22, wherein the alkanolamine orammonia, or both, are each in an amount less than 1% by weight of thecomposition and the aqueous carrier.
 24. The composition of claim 21,wherein the sparingly soluble copper salt is substantially crystalline.25. The composition of claim 24, wherein the sparingly soluble coppersalt is selected from the group consisting of copper borate, basiccopper borate, copper carbonate, basic copper carbonate, tribasic coppersulfate, copper oxychloride, alkaline copper nitrate, copperferricyanate, copper fluorosilicate, copper thiocyanate, copperdiphosphate, copper boride, copper phosphate, copper hydroxide andmixtures thereof.
 26. The composition of claim 23, wherein thealkanolamine or ammonia, or both, are each in an amount less than 0.1%by weight of the composition and the aqueous carrier.
 27. Thecompositions of claim 23, wherein the alkanolamine or ammonia, or both,are each in an amount less than 1% by weight of the copper.
 28. Thecompositions of claim 21, wherein the composition comprises at least oneorganic biocide.
 29. The composition of claim 28, wherein said organicbiocide is an amine present in an amount which is not part of the amountof alkanolamine or ammonia present in the amount of less than 10% byweight of the composition and the aqueous carrier.
 30. The compositionof claim 28, wherein at least a portion of the organic biocide is coatedon the milled particles.